Cancer-related neuropathic pain

Infection by the human immunodeficiency virus (HIV) causes depletion of CD4-positive lymphocytes with consequent immunodeficiency. HIV infection also causes, by direct or indirect mechanisms, both reactive and neoplastic changes in lymphoid tissues. In primary infection reactive changes are a direct response to HIV. Later in the course of the disease there are reactive changes in lymph nodes and extranodal lymphoid tissues which are likely to be largely an indirect effect of HIV infection, being a response to opportunistic infection by other organisms. There is also an increased incidence of autoimmune phenomena in HIV-infected subjects which is likely to be consequent, at least in part, on impaired control of the proliferation of self-reactive B-cell clones. A second mechanism of immune damage of blood cells, probably operating in the case of HIV-related immune thrombocytopenic purpura, is that of cellular damage by immune complexes containing antiviral antibodies. Lymphoid neoplasms associated with HIV infection include non-Hodgkin's lymphoma, Hodgkin's disease and, uncommonly, plasma cell dyscrasias. HIV-associated lymphomas have distinct clinicopathological features and generally a poor prognosis. As for reactive lymphoid lesions, induction of neoplasia is likely, in the majority of cases, to be an indirect rather than a direct effect of the virus. The combination of chronic B-cell stimulation and impaired T-cell function is important, and interaction of lymphoid cells with virus-infected stromal cells may also play a role. Infection by oncogenic viruses such as the Epstein-Barr virus and human herpes virus 8 is also aetiologically important. In rare cases of T-cell lymphoma, HIV may be directly oncogenic.     

v-representability for noninteracting systems

The Epstein-Barr virus (EBV) induces unlimited growth of B lymphocytes in vitro, a phenomenon known as immortalization. The elucidation of the mechanisms by which EBV de-regulates B-cell proliferation in vitro will permit an understanding of how the virus contributes in vivo to the genesis of Burkitt's lymphoma (BL) and of lymphoproliferations in immunosuppressed patients. At present, no single EBV immortalizing gene has been identified, and the hypothesis has been made that many viral genes cooperate in establishing an autocrine loop of secretion leading to immortalization. Constitutive expression of B-cell surface molecules such as CD21 and CD23, specifically implicated in the control of B-cell proliferation, is indeed induced at the surface of immortalized B lymphocytes. The expression of the viral nuclear antigen 2 (EBNA2) has been shown to be in part responsible for CD21 and CD23 up-regulation, and EBNA2 is suspected to be a transactivator of cellular genes, although this point remains to be demonstrated. The role of EBNA2 gene, independently of other viral genes, has been investigated by transfection into B-lymphoma lines, but conflicting results have been reported. To further investigate its role in the regulation of CD21 and CD23 molecules, we have compared the effects of EBNA2 expression in 2 sets of B-lymphoma lines infected with P3HR1 EBV strain, and/or transfected with EBNA2 gene. We report here that: (i) EBNA2 expression is not a sufficient condition to induce CD21 and CD23 upregulation, EBNA2's effects are highly dependent on the cellular context, and moreover can be modified by infection with P3HR1 virus; (ii) EBNA2 induces activation of CD23 expression in a very particular way, namely, an increased quantity of CD23 steady-state RNA coding for the form A of the protein, which is not detectable at the cell surface but directly secreted.     

Demonstration of the Th1 to Th2 cytokine shift during the course of HIV-1 infection using cytoplasmic cytokine detection on single cell level by flow cytometry

OBJECTIVE: To characterize changes of Th1/Th2 cytokine production by peripheral blood mononuclear cells (PBMC) that occur during the course of HIV infection by cytoplasmic cytokine staining on single cell level. DESIGN AND METHODS: Mitogen-stimulated PBMC from 16 healthy donors, 18 HIV-1-infected individuals without AIDS and 14 patients with AIDS were stained intracellularly with fluorescein-labelled MAb against interleukin (IL)-2, IL-4, IL-10 and interferon (IFN)-gamma. Additionally, co-staining of CD4+ T-cell, CD8+ T-cell, natural killer (NK) cell, B-cell and monocytic markers was performed. Fluorescence staining was analysed by three-colour flow-cytometry. RESULTS: A reduced percentage of IL-2 and IFN-gamma (Th1 type)-producing cells among CD4+ T cells from HIV-1-infected individuals could be demonstrated. There was a continuous decrease of IFN-gamma-producing CD4+ T cells in the course of HIV infection and a dramatic reduction of IL-2-expressing cells among CD4+ T cells in patients with AIDS. In contrast to Th1 cytokines, the frequency of Th2 cytokine expressing cells among CD4+ T cells increased in HIV-infected individuals. The maximum frequency of IL-4-expressing cells among CD4+ T cells was seen in HIV-infected individuals without AIDS, whereas the rate of IL-10-producing cells was highest in patients with AIDS. In HIV-infected individuals no significant proportion of Th0 cells expressing both Th1 and Th2 cytokines was detectable. In CD8+ T cells the percentage of IL-2 was expressing cells decreased continuously accompanied by a strong increase of the frequency of IFN-gamma-producing cells. CONCLUSION: The decreased percentage of cells expressing IL-2 and IFN-gamma in conjunction with an increased proportion of IL-4- and IL-10-producing cells among the CD4+ T cells in HIV-1-infected individuals demonstrate a Th1 to Th2 cytokine shift in the course of HIV infection on a single cell level. There was no evidence of a Th1 to Th0 cytokine shift. In addition to the loss of CD4+ T cells in HIV infection, the qualitative changes of Th1/Th2 cytokine expression may serve as a marker for progressive failure of cell-mediated immunity.     

The theory and practice of health education applied to nursing: a bi-polar approach

Because CD1-restricted T cells lack CD4 but produce IFN-gamma in response to nonpeptide mycobacterial antigens, they could play a unique role in immunity to tuberculosis. We studied CD1-restricted T cells in the context of HIV infection by expanding CD4(-) T cell lines from 10 HIV-infected patients. Upon stimulation with Mycobacterium tuberculosis antigen or upon exposure to macrophages infected with M. tuberculosis, these T cell lines proliferated, produced IFN-gamma, and showed cytolytic T cell (CTL) activity against macrophages pulsed with mycobacterial antigen, findings consistent with a protective role against M. tuberculosis. Anti-CD1b antibodies abrogated T cell proliferation, IFN-gamma production, and CTL activity, demonstrating that these T cells are CD1 restricted. IFN-gamma production in response to M. tuberculosis was enhanced by antitransforming growth factor-beta in 8/10 lines, and by IL-15 in 2/10 lines. IFN-gamma production was augmented in a nonantigen-specific manner by IL-12 in 4/8 lines. When live HIV was cocultured with CD1-restricted T cell lines, p24 antigen and proviral DNA were not detected, indicating that the T cells were not infectable with HIV. Vaccination strategies aimed at activation and expansion of M. tuberculosis-reactive CD1-restricted T cells in HIV-infected patients may constitute a novel means to provide protection against tuberculosis, while minimizing the risk of enhancing HIV replication through stimulation of CD4(+) cells.     

Distinct biology of Kaposi's sarcoma-associated herpesvirus from primary lesions and body cavity lymphomas

The DNA sequence for Kaposi's sarcoma-associated herpesvirus was originally detected in Kaposi's sarcoma biopsy specimens. Since its discovery, it has been possible to detect virus in cell lines established from AIDS-associated body cavity-based B-cell lymphoma and to propagate virus from primary Kaposi's sarcoma lesions in a human renal embryonic cell line, 293. In this study, we analyzed the infectivity of Kaposi's sarcoma-associated herpesvirus produced from these two sources. Viral isolates from cultured cutaneous primary KS cells was transmitted to an Epstein-Barr virus-negative Burkitt's B-lymphoma cell line, Louckes, and compared to virus induced from a body cavity-based B-cell lymphoma cell line. While propagation of body cavity-based B-cell lymphoma-derived virus was not observed in 293 cell cultures, infection with viral isolates obtained from primary Kaposi's sarcoma lesions induced injury in 293 cells typical of herpesvirus infection and was associated with apoptotic cell death. Interestingly, transient overexpression of the Kaposi's sarcoma-associated herpesvirus v-Bcl-2 homolog delayed the process of apoptosis and prolonged the survival of infected 293 cells. In contrast, the broad-spectrum caspase inhibitors Z-VAD-fmk and Z-DEVD-fmk failed to protect infected cell cultures, suggesting that Kaposi's sarcoma-associated herpesvirus-induced apoptosis occurs through a Bcl-2-dependent pathway. Kaposi's sarcoma-associated herpesvirus isolates from primary Kaposi's sarcoma lesions and body cavity-based lymphomas therefore may differ and are likely to have distinct contributions to the pathophysiology of Kaposi's sarcoma.     

Increased expression of CD80, CD86 and CD70 on T cells from HIV-infected individuals upon activation in vitro: regulation by CD4+ T cells

T cells express CD28 and CD27 which transduce co-stimulatory signals after interaction with their ligands on antigen-presenting cells (APC). These ligands, CD80, CD86 and CD70, are also expressed to some extent on activated T cells. Here, we show that in human immunodeficiency virus (HIV)-infected individuals, CD28 and CD27 expression is decreased on CD8+ T cells. On the other hand, T cell stimulation in vitro induced high CD80, CD86 and CD70 expression on T cells from HIV-infected individuals. It appeared that an inverted CD4:CD8 T cell ratio could explain this enhanced expression of co-stimulatory ligands. Indeed, high expression levels of CD80, CD86 and CD70 were found on activated CD8+ T cells from HIV- individuals cultured in the absence of CD4+ T cells. Addition of CD4+ T cells prevented this up-regulation. However, in HIV-infected individuals, addition of excess autologous or healthy control CD4+ T cells did not completely counteract up-regulation of co-stimulatory ligand expression on CD8+ T cells. Thus, to some extent, CD8+ T cells in HIV-infected individuals appeared to be refractory to CD4+ T cell-mediated regulation of ligand expression in vitro. Activated T cells from HIV-infected individuals and activated CD8+ T cells from healthy controls were able to act as accessory cells in CD3-induced T cell proliferation, which was dependent on cell-cell contact. Thus, we showed that T cells from HIV-infected individuals express enhanced levels of co-stimulatory ligands upon activation, which provides them with accessory cell properties. Enhanced stimulatory potential of these nonprofessional APC may contribute to persistently high levels of immune activation in HIV infection related to disease progression.     

CD40 ligand and autoantigen are involved in the pathogenesis of low-grade B-cell lymphomas of mucosa-associated lymphoid tissue

Low-grade MALT-type lymphomas are malignancies of mucosal marginal-zone B cells and preceded by reactive inflammatory lymphoid tissue. Experimental observations suggest that antigen and CD40 Ligand act during cognate T/B cell interaction and are crucial for germinal center B-cell maturation generating marginal-zone B cells. To investigate the mechanisms underlying the development of extranodal MALT-type lymphomas, the immunoglobulin receptor was sequenced and analyzed for antigen specificity using heterohybridoma technology. Furthermore, CD40 ligand expression was evaluated by immunohistochemistry and by semiquantitative RT-PCR, and ligand binding to the CD40 of tumor B cells was studied using the CD40 system. Hypermutations were found in low-grade lymphomas throughout CDR1-CDR3 suggestive of positive selection through their antigen receptor. Different VH families were used and more than 69% of tumor immunoglobulins bound different mucosal antigens. CD40L expression was found in the tumor marginal zone in substantial amounts. The in vitro proliferation response of all low-grade MALT-type lymphomas was dependent on anti-CD40-mediated signals and cytokines. Our data provide evidence that autoantigen as well as the CD40L expressed by activated nonneoplastic T cells may drive the evolution of low-grade MALT-type lymphomas either directly or by paracrine mechanisms and that antigen may contribute to lymphoma pathogenesis.     

Cystic prostatic disease associated with adrenocortical lesions in the ferret (Mustela putorius furo)

CONTEXT: In British Columbia, human immunodeficiency virus (HIV)-infected persons eligible for antiretroviral therapy may receive it free but the extent to which HIV-infected injection drug users access it is unknown. OBJECTIVE: To identify patient and physician characteristics associated with antiretroviral therapy utilization in HIV-infected injection drug users. DESIGN: Prospective cohort study with record linkage between survey data and data from a provincial HIV/AIDS (acquired immunodeficiency syndrome) drug treatment program. SETTING: British Columbia, where antiretroviral therapies are offered free to all persons with HIV infection with CD4 cell counts less than 0.50 x 10(9)/L (500/microL) and/or HIV-1 RNA levels higher than 5000 copies/mL. SUBJECTS: A total of 177 HIV-infected injection drug users eligible for antiretroviral therapy, recruited through the prospective cohort study since May 1996. MAIN OUTCOME MEASURES: Patient use of antiretroviral drugs through the provincial drug treatment program and physician experience treating HIV infection. RESULTS: After a median of 11 months after first eligibility, only 71 (40%) of 177 patients had received any antiretroviral drugs, primarily double combinations (47/71 [66%]). Both patient and physician characteristics were associated with use of antiretroviral drugs. After adjusting for CD4 cell count and HIV-1 RNA level at eligibility, odds of not receiving antiretrovirals were increased more than 2-fold for females (odds ratio [OR], 2.53; 95% confidence interval [CI], 1.08-5.93) and 3-fold for those not currently enrolled in drug or alcohol treatment programs (OR, 3.49; 95% CI, 1.45-8.40). Younger drug users were less likely to receive therapy (OR, 0.47/10-y increase; 95% CI, 0.28-0.80). Those with physicians having the least experience treating persons with HIV infection were more than 5 times less likely to receive therapy (OR, 5.55; 95% CI, 2.49-12.37). CONCLUSIONS: Despite free antiretroviral therapy, many HIV-infected injection drug users are not receiving it. Public health efforts should target younger and female drug users, and physicians with less experience treating HIV infection.     

Activation of CD8+ T lymphocytes through the T cell receptor turns on CD4 gene expression: implications for HIV pathogenesis

T cell activation through the T cell receptor is necessary to achieve a specific and effective immune response. We report here that stimulation of CD8+ T cells through the T cell receptor complex leads to de novo expression of the CD4 antigen on the cell surface that results in susceptibility of CD8+ T cells to HIV infection. In addition, activation of peripheral blood mononuclear cells from HIV-infected individuals results in the appearance of double-positive CD4+/CD8+ T cells, which become infected by endogenous HIV. HIV DNA sequences could be detected in uncultured and sorted mature CD3+CD8+ T cells from HIV+ individuals. These results suggest a new mechanism by which HIV could attack the immune system and may help to explain the CD8+ T cell defects in AIDS patients.     

Role of macrophages in the pathogenesis of human immunodeficiency virus (HIV) infection

There are a number of machanisms by which HIV-infected macrophages contribute to the pathogenesis of the Acquired Immunodeficiency Syndrome (AIDS). Macrophage-tropic strains of HIV are present at the time of infection, and persist throughout the course of infection, despite the emergence of T cell tropic quasispecies. As HIV causes chronic infection of macrophages with only minimal cytopathology, these cells can provide an important viral reservoir in HIV-infected persons. Macrophages are more susceptible to HIV infection than freshly isolated monocytes. HIV-infected macrophages can contribute to CD4 T lymphocyte depletion through a gp120-CD4 dependent fusion process with uninfected CD4-expressing T cells. Increasing data support the role of HIV-infected macrophages and microglia in the pathogenesis of HIV-related encephalopathy and AIDS-related dementia through the production of neurotoxins. HIV infection of macrophages in vitro results in impairment of many aspects of their function. Reduced phagocytic capacity for certain opportunistic pathogens, including Toxoplasma gondii and Candida albicans, may be responsible for reactivation of these pathogens in persons with advanced HIV infection, although the mechanisms underlying reactivation of infections and susceptibility to disease from new infections are likely to be multifactorial. Our studies showing defective phagocytosis and killing provide additional information that contribute to our understanding of the pathogenesis of AIDS. Studies of in vitro efficacy of potential antiretroviral therapies should be performed in both primary lymphocyte and monocyte cultures, given the importance of both of these cell populations to HIV pathogenesis and their differing biology.     

Effect of B-cell receptor engagement on CD40-stimulated B cells

Activation of human B cells in vitro either by cross-linking of surface immunoglobulins (sIg) or by triggering CD40 antigen, in the presence of interleukin-10 (IL-10) and interleukin-2 (IL-2), may result in high levels of immunoglobulin secretion in vitro. We studied the combined effects of ligation of the B-cell receptor (BCR) and CD40 [with anti-CD40 monoclonal antibody (mAb)] on B-cell proliferation and production of human immunoglobulin. For this purpose highly purified splenic B cells were cultured with various combinations of anti-CD40 and IL-10/IL-2 or IL-4 in the presence of CD32-transfected L cells. Simultaneous cross-linking of the BCR was achieved by mAb held on CD32-L cells or Staphylococcus aureus (SA). We found that dual BCR and CD40 ligation with IL-10/IL-2 leads to reduced immunoglobulin G (IgG) secretion compared with B cells stimulated with either anti-CD40 and IL-10/IL-2, or compared with B cells stimulated with SA or anti-BCR mAb and IL-10/IL-2. Dual BCR and CD40 ligation with anti-immunoglobulin mAb (anti-kappa + anti-lambda light chains) but not with SA induced a similar reduction in IgM production. The reduced immunoglobulin secretion found during dual ligation is accompanied by increased proliferation. This was independent of cytokine stimulation but SA/CD40-induced proliferation was increased in the presence of IL-10/IL-2, although not with IL-4. The combination anti-kappa and anti-lambda with anti-CD40 showed a long-term suppression of IgG and IgM production (at least 14 days), while anti-kappa or anti-lambda alone, or SA, allowed a moderate recovery of immunoglobulin production by day 14. These results suggest that simultaneous B-cell antigen receptor cross-linking and CD40 engagement via CD40L on T cells induces strong initial proliferation. This may be followed later by antibody production depending on the strength of the BCR signal and the presence of the appropriate cytokines.     

Chronic lymphocytic leukemia B cells can express CD40 ligand and demonstrate T-cell type costimulatory capacity

Chronic lymphocytic leukemia (CLL) is characterized by a clonal expansion of CD5(+) B cells in the peripheral blood. Associated immune aberrations include abnormal Th-cell function and pathogenic autoantibodies. Under most circumstances, CLL B cells do not proliferate in culture and express a limited repertoire of surface antigens, including CD19, CD20, CD23, CD27, CD40, and CD70. In this report, we demonstrate that freshly isolated B cells from a subset of CLL cases constitutively express CD40 ligand (CD40L, CD154), a member of the tumor necrosis factor family which is normally expressed by activated CD4(+) T cells and mediates T-cell-dependent B-cell proliferation and antibody production. The degree of CD40L expression varied considerably among the CLL cases examined. CD40L was detected in purified CLL B cells by immunofluorescence flow cytometry, by RT-PCR, and by immunoprecipitation. To demonstrate that CD40L in the CLL B cells is functional, we used irradiated CLL cells to stimulate IgG production by target, nonmalignant B cells in coculture. The CLL B cells induced IgG production by normal B cells to a similar degree as did purified T cells in a process which was partially inhibited by monoclonal antibody to CD40L. This is one of the first reports of CD40L expression in a B-cell tumor. The data suggest that CD40L in the tumor cells may be a factor in the generation of pathologic antibodies by normal B cells in some patients with CLL.     

CD30 ligand is frequently expressed in human hematopoietic malignancies of myeloid and lymphoid origin

CD30 ligand (CD30L) is a type-II membrane glycoprotein capable of transducing signals leading to either cell death or proliferation through its specific counterstructure CD30. Although several lines of evidence indicate that CD30L plays a key role as a paracrine- or autocrine-acting surface molecule in the deregulated cytokine cascade of Hodgkin's disease, little is known regarding its distribution and biologic significance in other human hematopoietic malignancies. By analyzing tumor cells from 181 patients with RNA studies and immunostaining by the anti-CD30L monoclonal antibody M80, we were able to show that human hematopoietic malignancies of different lineage and maturation stage display a frequent and broad expression of the ligand. CD30L mRNA and surface protein were detected in 60% of acute myeloid leukemias (AMLs), 54% of B-lineage acute lymphoblastic leukemias (ALLs), and in a consistent fraction (68%) of B-cell lymphoproliferative disorders. In this latter group, hairy cell leukemia and high-grade B-cell non-Hodgkin's lymphoma (B-NHL) expressed a higher surface density of CD30L as compared with B-cell chronic lymphocytic leukemia and low-grade B-NHL. Purified plasmacells from a fraction of multiple myeloma patients also displayed CD30L mRNA and protein. A more restricted expression of CD30L was found in T-cell tumors that was mainly confined to neoplasms with an activated peripheral T-cell phenotype, such as T-cell prolymphocytic leukemia, peripheral T-NHL, and adult T-cell leukemia/lymphoma. In contrast, none of the T-lineage ALLs analyzed expressed the ligand. In AML, a high cellular density of CD30L was detected in French-American-British M3, M4, and M5 phenotypes, which are directly associated with the presence on tumor cells of certain surface structures, including the p55 interleukin-2 receptor alpha-chain, the alpha(M) (CD11b) chain of beta2 integrins, and the intercellular adhesion molecule-1 (CD54). Analysis of normal hematopoietic cells evidenced that, in addition to circulating and tonsil B cells, a fraction of bone marrow myeloid precursors, erythroblasts, and subsets of megakaryocytes also express CD30L. Finally, we have shown that native CD30L expressed on primary leukemic cells is functionally active by triggering both mitogenic and antiproliferative signals on CD30+ target cells. As opposed to CD30L, only 10 of 181 primary tumors expressed CD30 mRNA or protein, rendering therefore unlikely a CD30-CD30L autocrine loop in human hematopoietic neoplasms. Taken together, our data indicate that CD30L is widely expressed from early to late stages of human hematopoiesis and suggest a regulatory role for this molecule in the interactions of normal and malignant hematopoietic cells with CD30+ immune effectors and/or microenvironmental accessory cells.     

T cell cytokine responses in persons with tuberculosis and human immunodeficiency virus infection

Tuberculosis causes more extensive and life-threatening disease in patients with HIV infection than in immunocompetent persons. To investigate the hypothesis that these severe manifestations of tuberculosis may be due to alterations in cytokine production, we evaluated cytokine patterns in HIV-infected tuberculosis patients. Upon stimulation with Mycobacterium tuberculosis in vitro, PBMC from HIV-infected tuberculosis patients had reduced proliferative and type 1 responses, compared with HIV-seronegative tuberculosis patients. The reduction in proliferative responses was independent of the CD4 cell count, but the reduced type 1 response was a direct result of CD4 cell depletion. There was no enhancement of type 2 cytokine production in HIV-infected patients, although production of IL-10 was prominent in all tuberculosis patients. In HIV-infected tuberculosis patients, M. tuberculosis-induced proliferative responses were significantly enhanced by neutralizing antibodies to IL-10 but not by antibodies to IL-4 or by recombinant IL-12. The M. tuberculosis-induced type 1 response was augmented both by antibodies to IL-10 and by recombinant IL-12. Tuberculosis in the context of HIV infection is characterized by diminished type 1 responses, probably induced by immunosuppressive cytokines produced by macrophages/monocytes, rather than by type 2 cells.     

Cytokines regulate expression and function of the HIV coreceptor CXCR4 on human mature dendritic cells

HIV-infected dendritic cells (DC) efficiently transmit infection to CD4+ T cells during the process of T cell activation. To further understand interactions between DC and HIV, cytokine regulation of HIV coreceptors on cultured Langerhans cells (cLC, as prototypes of mature DC) was studied. Expression of cell surface CXCR4 on cLC was up-regulated by IL-4 and TGF-beta1 and inhibited by IFN-alpha, IFN-beta, and IFN-gamma, whereas cytokines did not appreciably regulate CCR5. Changes in cell surface CXCR4 expression on cLC correlated with T cell-tropic (X4)-HIV envelope-mediated syncytium formation and X4-HIV infection levels. A relative increase in the ratio of type 2/type 1 cytokine production, which can occur in HIV disease, may up-regulate CXCR4 expression on mature DC and promote infection by X4 viruses. Importantly, these findings suggest that cytokine dysregulation may be linked to the emergence of X4-HIV strains as HIV-infected individuals progress to AIDS.     

Ligation of CD40 potentiates Fas-mediated activation of the cysteine protease CPP32, cleavage of its death substrate PARP, and apoptosis in Ramos-Burkitt lymphoma B cells

The proliferation and survival of a B cell population is necessarily tightly controlled to prevent the arisal of malignancy or autoimmunity. The expansion or elimination of a B cell clone is determined through a complex interaction of the tumour necrosis factor receptor/nerve growth factor receptor family members CD40 and Fas, which are expressed on the B cell surface, with their respective physiological ligands (CD40L and FasL) expressed on the surface of CD4+ T cells. The regulation of B cell growth by signals transduced through CD40 and Fas contributes to the maintenance of peripheral tolerance and likely takes place and in the germinal centres (GC) of secondary lymphoid tissues. In this study, we investigate the relationship between the expression of Fas and B cell survival following engagement of CD40 and Fas in the Epstein-Barr virus-genome-negative Ramos-Burkitt lymphoma (Ramos-BL) B cell line model of GC B lymphocyte selection during maturation of the humoral immune response. We now present evidence that Ramos-BL B cells constitutively express both Fas and FasL on their surface and that expression of Fas, but not FasL, is enhanced following ligation of CD40. Coligation of CD40 and Fas, triggers for growth inhibition, activation of the interleukin-1 beta-converting enzyme, now caspase, family member CPP32 (caspase-3) but not Ich-1L (caspase-2), cleavage of its death substrate poly(ADP-ribose) polymerase, and apoptosis from the G1 phase of cell cycle; engagement of Fas alone fails to trigger for growth inhibition and apoptosis but enhances AgR-mediated cellular death. This CD40-potentiated Fas-triggered growth inhibition and apoptosis occurs in the presence of CD40-induced expression of the anti-apoptotic proteins Bcl-xL and Bcl-2. Taken together, these data indicate that ligation of CD40 facilitates efficient coupling of Fas to the caspase-mediated pathway of apoptosis.     

The B7/BB1 antigen is expressed by Reed-Sternberg cells of Hodgkin's disease and contributes to the stimulating capacity of Hodgkin's disease-derived cell lines

The B7/BB1 molecule has recently been found to be expressed on professional antigen-presenting cells and to be the natural ligand for CD28 and CTLA-4 on T cells. On binding of B7/BB1, CD28 transduces a signal that synergizes with triggering of the T-cell antigen receptor, resulting in enhanced cytokine secretion. In view of the data supporting an antigen-presenting function of Reed-Sternberg cells, we evaluated the expression of B7/BB1 in lymph nodes affected by Hodgkin's disease. B7/BB1 was found to be strongly expressed by the Reed-Sternberg cells in all 47 cases of Hodgkin's disease studied. Moreover, Reed-Sternberg cells were frequently surrounded by CD28-expressing T cells. Evidence for a functional role of B7/BB1 on Reed-Sternberg cells was obtained by our findings that T-cell proliferation and interleukin-2 (IL-2) production in the primary allogenic mixed lymphocyte reaction (MLR), using the B7/BB1-expressing Hodgkin's disease-derived cell lines L428 and KM-H2 as stimulators, could be partially blocked by adding anti-B7 monoclonal antibody. B7/BB1 expression was also evaluated in a group of non-Hodgkin's lymphomas (n = 46). Whereas B7/BB1 was not expressed by the neoplastic cells of most non-Hodgkin's lymphomas, including T-cell-rich B-cell lymphoma (n = 11), it was present on the neoplastic cells of anaplastic large-cell lymphoma (Ki-1 lymphoma) (n = 5) and follicular lymphoma (n = 4). Our data provide further evidence for an accessory cell function of Reed-Sternberg cells. The accessory cell function of Reed-Sternberg cells might lead to pronounced T-cell activation in vivo, which might contribute to the Hodgkin's syndrome. In addition, our study indicates that B7/BB1 may be a useful marker for differentiating Hodgkin's disease from morphologically similar conditions such as T-cell-rich B-cell lymphoma.     

T-cell activation induced by anti-CD3 x anti-B-cell lymphoma monoclonal antibody is enhanced by pretreatment of lymphoma cells with soluble CD40 ligand

T cells play a key role in the control of abnormal B cell proliferation. Factors that play a role in inadequate T cell responses include absence of expression of costimulatory and adhesion molecules by the malignant B cells and lack of cytotoxic T cells specific for tumor-associated antigens. A number of approaches have been used to enhance T cell response against malignant B cells. Agents such as soluble CD40 ligand can enhance expression of costimulatory molecules by the malignant B cells and improve their ability to activate T cells. Anti-CD3-based bispecific antibodies can retarget T cells toward the tumor cells irrespective of T cell specificity. We used the V 38C13 murine lymphoma model to assess whether the combination of soluble CD40 ligand and anti-CD3-based bispecific antibody can enhance T cell activation induced by malignant B cells more effectively than either approach alone. Expression of CD80, CD86, and ICAM-1 on lymphoma cells was up-regulated by soluble CD40 ligand. Syngeneic T cells were activated more extensively by lymphoma cells when the lymphoma cells were pre-treated with soluble CD40 ligand. Bispecific-antibody induced T cell activation was more extensive when lymphoma cells pretreated with soluble CD40 ligand were present. The combination of soluble CD40 ligand plus bispecific antibody enhanced the median survival of mice compared to mice treated with bispecific antibody alone. We conclude that pretreatment of tumor cells with agents capable of inducing costimulatory molecule expression, such as soluble CD40 ligand can enhance the ability of malignant B cells to activate T cells. This effect is enhanced by the addition of bispecific antibody. The combination of enhanced expression of costimulatory molecules and retargeting of T cells by bispecific antibody may allow for a more effective T-cell-based immunotherapy.     

Primary CD8+ cells from HIV-infected individuals can suppress productive infection of macrophages independent of beta-chemokines

The productive infection of human monocyte-derived macrophages (Mphi) by HIV was suppressed by primary CD8+ cells from asymptomatic HIV-infected individuals. This anti-HIV response was noncytotoxic; removal of the CD8+ cells from the infected Mphi leads to virus production. CD8+ cells inhibited HIV replication when separated from the infected Mphi by a transwell filter insert, indicating a diffusible factor made by the CD8+ cells suppressed productive infection of Mphi. Three beta-chemokines, which can be secreted by activated CD8+ cells, RANTES (regulated on activation normal T cell expressed and secreted), macrophage inflammatory protein (MIP)-1alpha and MIP-1beta prevented HIV replication in the Mphi cultures. In addition, incubation of acutely infected Mphi with a mixture of neutralizing antibodies to RANTES, MIP-1alpha, and MIP-1beta enhanced virus replication. Nevertheless, neutralization of beta-chemokines with specific antibodies did not abolish the suppression by CD8+ cells of HIV replication in Mphi. Thus, even though beta-chemokines decrease HIV replication in Mphi, these cytokines are not responsible for the ability of CD8+ cells to inhibit HIV production in these cells.     

Seroconversion for human herpesvirus 8 during HIV infection is highly predictive of Kaposi's sarcoma

BACKGROUND: The finding of antibodies against human herpesvirus 8 (HHV-8) is associated with the occurrence of Kaposi's sarcoma in persons infected with HIV. However, the predictive value of HHV-8 antibodies for Kaposi's sarcoma in HIV infection is unknown. METHODS: The Amsterdam Cohort Studies on HIV infection and AIDS started in 1984 for homosexual men and in 1985 for injecting drug users. Serum samples from 1459 homosexual men and 1167 drug users were tested for antibodies to recombinant HHV-8 lytic-phase capsid (ORF65) antigen and latent-phase nuclear (ORF73) antigen. Individuals were retrospectively identified as HHV-8-positive or HHV-8-negative at enrolment or HHV-8 seroconverter during the study. Kaposi's sarcoma-free survival time was compared between HIV-infected men who were positive for HHV-8 at enrolment and those who later seroconverted for HHV-8. Hazard ratios were estimated for Kaposi's sarcoma, lymphoma, and opportunistic infection according to the HHV-8 serostatus. RESULTS: The incidence of HHV-8 seroconversion among drugs users was 0.7 per 100 person-years based on 31 seroconversions, whereas an incidence of 3.6 was found among homosexual men based on 215 seroconversions. The hazard ratio for Kaposi's sarcoma was 3.15 (95% CI: 1.89-5.25) in HIV-infected individuals if HHV-8 antibodies were present either at enrolment or at HIV seroconversion. In HIV-infected persons who later seroconverted to HHV-8, Kaposi's sarcoma developed more rapidly: hazard ratio of 5.04 (95% CI: 2.94-8.64), an additional risk of 1.60 (95% CI: 1.01-2.53; P = 0.04). Time-dependent adjustment for CD4+ cell count and HIV RNA had no impact on the additional risk, although the CD4+ cell count was an independent risk factor for Kaposi's sarcoma. HHV-8 infection did not increase the risk of AIDS-related lymphoma or opportunistic infections. CONCLUSIONS: The incidence of HHV-8 infection is higher in homosexual men than in drug users. The presence of HHV-8 antibodies in HIV-infected persons increases the risk of Kaposi's sarcoma. Among HIV-infected persons, those who subsequently seroconvert for HHV-8 are at highest risk. These results strongly confirm the causal role of HHV-8 in Kaposi's sarcoma and emphasize the clinical relevance of HHV-8 seroconversion before and after the HIV infection.