T-stem cell leukemia/lymphoma with both myeloid lineage conversion and T-specific delta recombination

We evaluated retrospectively the clinical and biological characteristics of six patients with CD7+ early T-acute lymphoblastic leukemia and lymphoma (T-ALL/LBL) originating from prothymocyte stage I (pro-T I) or II cells. Patients exhibited mediastinal mass (five of six) and lymphoadenopathy (five of six) but without leukocytosis and circulating blast cells (six of six). All patients achieved a complete remission. All but one had a relapse with a transformation to the mixed type (triphenotype--three cases, biphenotype-two cases) including myeloid features in three patients. The altered phenotypes were myeloperoxidase (MPO)+ (three of five), CD13+ (four of five), CD33+ (three of five) and CD19+ (three of five). The difference for MPO-positivity were observed between the bone marrow (BM)- and lymph node (LN)-blast cells (three of three). On cytogenetic analysis, there is no common abnormality in these patients. Immunomolecular analysis revealed T-cell lineage specific delta gene rearrangements [D delta 2-J delta 1 (five of six) and V delta 1-J delta 1 (one of six)] in all cases. Furthermore, D delta 2-J delta 1 occurred even in the cases with the pro-T I phenotype. Rearrangements of TCR beta, gamma or immunoglobulin heavy chain genes occurred in three patients. The same rearranged band(s) appeared at both diagnosis and relapse, indicating the same originality of the pro-T leukemic cell clone (three of three). We suggest that this type of CD7+ early T-ALL/LBL was transformed from a pro-T I or II cell, such as T-stem cell leukemia/lymphoma, which is a subtype of CD7+ stem cell leukemia as defined by Kurtzberg et al. This study reveals that pro-T I and II cells might be capable of myeloid, T- and B-lymphoid differentiation, and T-cell lineage specific TCR delta recombination occurs.     

Treatment outcome of tacrine therapy depends on apolipoprotein genotype and gender of the subjects with Alzheimer''s disease

A novel interleukin-2 (IL-2)-dependent cell line, HANK1, was established from a patient with CD56+ NK/T-cell lymphoma arising in the retroperitoneum. Morphologically, HANK1 is a pleomorphic large cell line with irregular nuclei, which contains azurophilic granules in the cytoplasm. Immunophenotypic analysis showed that HANK1 expressed CD2, CD3epsilon, CD56, TIA-1, granzyme B, and HLA-DR, but no other T-lineage markers. These features were the same as seen in the original tumour, and are highly characteristic of nasal and 'nasal-type' NK/T-cell lymphoma as described in the proposed W.H.O. classification. Genotypically, this cell line also demonstrated the germline configuration of the T-cell receptor beta, gamma and the immunoglobulin heavy chain genes and clonal integration of the Epstein-Barr virus (EBV) together with antigen expression with a type II latency pattern (LMP-1+ and EBNA2-). Furthermore, Southern blot analysis using the EBV termini as probes confirmed its derivation from the original lymphoma, and revealed that it contained multiple copies of the EBV genome. Dose-dependent growth on IL-2 was observed in an in vitro study with a doubling time of 3 d at maximal stimulation. These data indicate that HANK1 seemed to preserve the biological characteristics of the original tumour and therefore may serve as a good model for the further analysis of unusual 'nasal-type' NK/T-cell lymphoma.     

Induction of the 2B9 antigen/dipeptidyl peptidase IV/CD26 on human natural killer cells by IL-2, IL-12 or IL-15

Activation of human natural killer (NK) cells involves sequential events including cytokine production and induction of cell surface molecules, resulting in the enhancement of cytolytic activity. To delineate the activation process of NK cells, we generated murine monoclonal antibodies (mAbs) against YT, a human large granular lymphocyte/natural killer (LGL/NK) cell line. Among the mAbs reactive with YT cells, one mAb, termed 2B9, was noted because of the lack of reactivity with most of the human T- and B-cell lines tested. In fresh peripheral blood mononuclear cells (PBMC), however, the majority of cells expressing this antigen (Ag) were T cells but not CD16+ nor CD56+ NK cells. Since YT cells showed an activated phenotype expressing interleukin-2 (IL-2) receptor alpha chain, we examined whether 2B9 Ag could be induced on normal human peripheral blood NK cells by cytokines known to activate NK cells. The 2B9 Ag was induced on NK cells by IL-2, IL-12 or IL-15 while no induction was observed by interferon-gamma (IFN-gamma). Biochemical analysis showed that anti-2B9 mAb recognized a 115 kDa molecule in YT cells. A cDNA clone encoding the 2B9 Ag was isolated from a cDNA expression library of YT cells and its sequence was identical to CD26 cDNA although it was not of full length. Transient expression of the 2B9 cDNA on COS-7 cells revealed that this cDNA encodes the antigenic epitope(s) recognized by anti-2B9 mAb as well as Ta1, an anti-CD26 mAb. These results showed that the 2B9 Ag is identical to CD26, and demonstrated that CD26 is an activation antigen on CD16+ CD56+ NK cells inducible by IL-2, IL-12 or IL-15.     

The expression of CD26 and CD40 ligand is mutually exclusive in human T-cell non-Hodgkin's lymphomas/leukemias

CD26 and CD40 ligand (CD40L) are surface molecules on human activated T lymphocytes that play a critical role in the regulation of lymphopoiesis. Both molecules are expressed on a restricted fraction of human T-cell non-Hodgkin's lymphomas (NHL)/leukemias; however, little is known about their functional and/or clinical significance in these disorders. In this study, the pattern of expression of CD40L was compared with that of the CD26 molecule. A series of 67 human T-cell NHL/leukemias and a panel of leukemia/lymphoma T-cell lines were evaluated by immunohistochemistry, flow cytometry, and RNA studies. The overall frequency of CD26+ and CD40L+ samples was rather similar (25/67 [37%] v 18/67 [27%]). However, the majority of CD26-expressing cases clustered in the lymphoblastic lymphomas (LBL)/T-acute lymphoblastic leukemias (ALL; 12/23) and CD30+ anaplastic large-cell (ALC) lymphomas (5/8), whereas CD40L+ lymphomas included a large fraction of mycosis fungoides (11/21 [52%]). CD26 and CD40L coexpression was found only in 2 myocosis fungoides cases and 1 small lymphocytic lymphoma. Thus, the expression of the two antigens was mutually exclusive in almost all T-cell lymphomas/leukemias. Accordingly, lymphoma cell lines expressed either one of the molecules or the relative amounts of CD26 and CD40L were inversely proportional. In contrast, reactive T lymphocytes from patients with non-neoplastic T-cell expansions and in vitro activated CD3+ or CD4+ normal T cells were found to coexpress CD40L and CD26. Results of a multivariate analysis showed that the expression of CD26 in T-cell LBL/ALL patients was associated to a worse outcome in terms of survival, as compared with patients with CD26- tumors (P < or = .0001). Based on our results, it can be concluded that, (1) as opposed to activated or reactive normal T cells, the expression of CD26 and of CD40L is mutually exclusive in human T-cell lymphomas/leukemias; (2) expression of CD26 is restricted to aggressive pathologic entities, such as T-cell LBL/ALL and T-cell CD30+ ALC lymphomas, whereas CD40L is expressed on slow progressing diseases such as mycosis fungoides; and (3) within the T-cell LBL/ALL group of tumors, CD26 may identify a subset of poor prognosis patients.     

Characterization of a novel human natural killer-cell line (NK-YS) established from natural killer cell lymphoma/leukemia associated with Epstein-Barr virus infection

A novel cell line was established from a patient with a leukemic-state nasal angiocentric natural killer (NK) cell lymphoma with systemic skin infiltration. The morphology of the leukemic cells was large-granular-lymphocyte (LGL), and their immunophenotype was CD2+, CD3-, CD5+, CD7+, CD16-, CD56+, and CD57-. The presence of Epstein-Barr viral (EBV) genome was shown in specimens from the patient's nose, skin, and peripheral blood by in situ hybridization using an EBV-encoded small RNA-1 probe or by Southern blotting using a terminal-repeat probe of the EBV genome. Leukemic cells were cocultured with a mouse stromal cell line (SPY3-2) in the presence of 100 U/mL recombinant human interleukin-2 and a novel stromal cell-independent cell line, NK-YS, was established. The NK-YS cells showed LGL morphology and expressed surface CD2, CD5, CD7, CD25, CD56, and CD95. The NK-YS cells retained cytotoxicity against K562 and Jurkat cells. A Southern blotting using a terminal-repeat probe of EBV showed that NK-YS and fresh leukemic cells had a clonal EBV genome, whereas the T-cell receptor beta and gamma chain genes of NK-YS were not rearranged. In an immunocytochemical analysis, the NK-YS cells showed a type-II latent infection of EBV. The NK-YS cells preserved the original characteristics of NK cell lymphoma/leukemia and will be a useful tool for the study of biological characteristics of EBV-associated nasal angiocentric NK cell lymphoma/leukemia.     

Calphostin C triggers calcium-dependent apoptosis in human acute lymphoblastic leukemia cells

Recent studies have demonstrated that the naturally occurring perylenequinone antibiotic calphostin C is a potent inhibitor of protein kinase C and can induce apoptosis in some tumor cell lines by an as yet unknown mechanism. Here we demonstrate that calphostin C induces dose-dependent apoptosis in DT40 chicken lymphoma B-cells, and targeted disruption of lyn, syk, btk, PLCgamma2, or IP3R genes does not prevent or attenuate its cytotoxicity. In our study, calphostin C also induced rapid apoptosis in human acute lymphoblastic leukemia (ALL) cell lines ALL-1 (BCR-ABL+ pre-pre-B ALL), RS4;11 (MLL-AF4+ pro-B ALL), NALM-6 (pre-B ALL), DAUDI (Burkitt's/B-cell ALL), MOLT-3 (T-ALL), and JURKAT (T-ALL), whereas other potent PKC inhibitors did not. In biochemical studies, calphostin C was discovered to induce rapid calcium mobilization from intracellular stores of ALL cell lines, and its cytotoxicity against ALL cell lines was well correlated with the magnitude of this calcium signal. Calphostin C-induced apoptosis was markedly suppressed by BAPTA/AM, a cell-permeable Ca2+ chelator as well as NiCl2, an inhibitor of Ca2+/Mg2+-dependent endonucleases. Inhibition of the Ca2+/calmodulin-dependent phosphatase calcineurin with perfluoreperazine dimadeate (a calmodulin antagonist) or cyclosporin A (a specific inhibitor of calcineurin) also reduced the magnitude of calphostin C-induced apoptosis in ALL cell lines. Calphostin C was capable of inducing calcium mobilization and apoptosis in freshly obtained primary leukemic cells from children with ALL. Taken together, our results provide unprecedented evidence that calphostin C triggers a Ca2+-dependent apoptotic signal in human ALL cells.     

CD4+ T cells inhibit growth of Epstein-Barr virus-transformed B cells through CD95-CD95 ligand-mediated apoptosis

Greater than 90% of the human population acquire Epstein-Barr virus (EBV) in infancy and retain a lifelong latent infection without any clinical consequences. Nevertheless EBV has been identified as the causal agent of infectious mononucleosis, and is associated with several tumours including endemic Burkitt's lymphoma and B cell lymphomas in immunosupressed patients. B cells infected with EBV are transformed in vitro and grow continuously as lymphoblastoid cell lines. The growth of EBV-transformed B cells in vivo is controlled by the immune system. Studies on immunity to EBV have mainly focused on MHC class I-restricted CD8+ cytotoxic T cells specific for viral latent antigens. Here it is reported that in vitro stimulation of peripheral blood lymphocytes by autologous EBV-infected B cells, which have been induced to express lytic cycle antigens, gives rise to a predominantly CD4+ T cell response. Furthermore, the growth of EBV-infected B cells can also be regulated by these activated CD4+ T cells through apoptosis mediated by CD95-CD95 ligand (CD95L). CD95-CD95L-mediated apoptosis is an important mechanism of normal B cell growth regulation. As EBV-transformed B cells remain susceptible to this mechanism, the control of EBV in vivo may be not only by virus-specific CD8+ cytotoxic T cell immunity but also by normal mechanisms of immune regulation of B cell growth.     

Targeting Epstein-Barr virus nuclear antigen 1 (EBNA1) through the class II pathway restores immune recognition by EBNA1-specific cytotoxic T lymphocytes: evidence for HLA-DM-independent processing

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is the only viral protein consistently expressed in all malignancies associated with EBV and there is now convincing evidence to suggest that EBNA1 is not recognized by MHC class I-restricted cytotoxic T lymphocytes (CTL). The lack of recognition of EBNA1 has been attributed to a cis-acting inhibitory effect of glycine-alanine repetitive (G-Ar) sequences on the endogenous processing of this antigen through the class I pathway. In the present study we have explored the possibility of targeting EBNA1 through an alternative mechanism using the MHC class II pathway. Using purified EBNA1 protein, we demonstrate here that CD4+ CTL can efficiently recognize EBV-transformed B cells and Burkitt's lymphoma cells following exogenous sensitization with this antigen, and this immune recognition is not affected by the G-Ar domain within EBNA1. Analysis of the processing mechanism revealed that intracellular loading of class II molecules with an EBNA1 epitope occurs through an HLA-DM-independent pathway. These results highlight a novel mechanism for immune recognition of EBNA1 and also demonstrate that the G-Ar-mediated protection from processing can be overridden if this antigen is presented through the class II pathway.     

Cellular characteristics of acute leukemia cells simultaneously expressing CD13/CD33, CD7 and CD19

Of 832 acute leukemia patients, including 580 acute myeloblastic leukemia (AML), 197 pre-B acute lymphoblastic leukemia (ALL) and 55 pre-T ALL, 26 cases (3.1%) of CD13/CD33+CD7+CD19+ acute leukemia were found. A total of 20 patients were diagnosed as AML, two as pre-B ALL and four as pre-T ALL. Based on the relative intensity of expression of CD7 and CD19, CD13/CD33+CD7+CD19+ acute leukemia patients were subclassified into three categories. Type I (CD7 > CD19) included ten AML and four pre-T ALL, having cellular characteristics similar to CD7+ AML and CD13/CD33+CD7+ ALL. Type II (CD7 < CD19) consisted of four AML with t(8;21) and two pre-B ALL. Type III (CD7 = CD19) included six AML. CD13/CD33+CD7+CD19+ acute leukemia frequently expressed stem cell associated molecules, such as CD34 (88.5%), HLA-DR (96.2%) and mRNA for MDR1 (72.2%), GATA-2 (87.5%) and SCL (25.0%). Simultaneous expression of cytoplasmic CD3 and myeloperoxidase in some leukemia cells implies that CD13/CD33+CD7+CD19+ acute leukemia cells have the potential to differentiate into various lineages. These data suggest that a small population of acute leukemia patients with distinct phenotype, CD13/CD33+CD7+CD19+ acute leukemia, may originate from hematopoietic stem cells.     

Detection of Epstein-Barr virus in transformations of low-grade B-cell lymphomas after fludarabine treatment

Fludarabine is a highly effective chemotherapeutic agent for chronic lymphocytic leukemia/small lymphocytic lymphoma and is also active in other B-cell lymphoproliferative disorders. Although highly efficacious in destroying the malignant B-cells, fludarabine also causes T-cell lymphopenia and immunosuppression. We present five patients given fludarabine for low-grade B-cell lymphoproliferative disorders who showed transformation of the primary neoplasm to a higher grade tumor. Immunohistologic antibody studies were performed on paraffin-embedded tissue sections of the initial tissue (when available) and on the follow-up biopsy specimens for CD20, CD3, CD45RO, CD43, CD30, CD15, and latent membrane protein (LMP-1) for Epstein-Barr virus (EBV). The initial diagnoses in these five patients included chronic lymphocytic leukemia/small lymphocytic lymphoma (three cases), follicle center lymphoma (one case), and Waldenstrom's macroglobulinemia (one case). All of the follow-up biopsy specimens showed scattered Hodgkin's-like cells, and two of the five also showed foci of large-cell transformation. The Hodgkin's-like cells showed CD30 immunoreactivity in four of the five cases and CD15 immunoreactivity in three of the five. Strong immunoreactivity of the large, atypical, Hodgkin's-like cells for LMP-1 of EBV was noted in four cases; in the remaining case, this finding was equivocal. In situ hybridization for EBV-encoded RNA was positive in four of the five cases. Molecular studies by polymerase chain reaction (PCR) showed the presence of EBV in three of the five cases. PCR for detection of immunoglobulin heavy chain demonstrated identical monoclonal rearrangements in the original lymphoma and transformation in one case with available material. The CD4 lymphocyte count in each patient was less than 550/microL, indicating cellular dysfunction. Transformation of low-grade non-Hodgkin's lymphomas after fludarabine therapy might be associated with EBV and severe immunosuppression.     

Lack of correlation between EBV serology and presence of EBV in the Hodgkin and Reed-Sternberg cells of patients with Hodgkin's disease

Epstein-Barr virus (EBV) is detected in Hodgkin and Reed-Sternberg (HRS) cells in up to 50% of patients with Hodgkin's disease (HD). HD patients have been reported to express high serum titers against EBV antigens, even prior to the diagnosis of HD. Patients with high serum titers have a poorer prognosis. The aim of this study was to examine the relationship between the presence of EBV in HRS cells and the antibody titers reactive with different EBV antigens. Frozen serum and histopathological tissues were available from 107 untreated HD patients diagnosed between 1979 and 1991. The presence of EBV in the HRS cells was evaluated with immunohistochemistry directed against the LMP-1 antigen and/or with in situ hybridization of EBER-1. Analyses were performed of serum titers against early antigen (EA), diffuse (IgA and IgG) and restricted (IgG), virus-capsid antigen (VCA) (IgA and IgG), and EBV-encoded nuclear antigens (EBNA, EBNA 1, EBNA 2A, EBNA 2B, EBNA 6). EBV was detected in 27/107 (25%) tumor specimens, with a higher proportion in the MC group 8/13 (62%) (p < 0.01). IgG VCA and EBNA were detected in 99/107 (93%), evidence of a previous EBV infection. There were no significant relationships between antibody titers reactive with different EBV antigens and detectable EBV in HRS cells. Furthermore, there did not appear to be any relationship between EBV serology or the presence of EBV in HRS cells and clinical outcome. The role of EBV in the development of HD, especially its relationship to the immunological response, remains unclear.     

Presence of Epstein-Barr virus in lymphoepithelioma-like carcinoma of the middle ear

AIM: To examine the association of Epstein-Barr virus (EBV) with carcinoma of the ear. METHODS: Five non-keratinising squamous cell carcinomas and two undifferentiated carcinomas of the ear were examined. In situ hybridisation was used to localised EBV-encoded RNAs (EBER). Immunohistochemical methods to detect LMP-1 and EBNA2 were performed in the EBER positive cases. RESULTS: Two cases were EBER positive, including one non-keratinising and one undifferentiated carcinoma. Both showed identical morphology to those arising from the nasopharynx, with abundant lymphoid stroma. They were both negative for LMP-1 and EBNA2. CONCLUSIONS: EBV associated carcinoma with the morphology of lymphoepithelioma can also arise from the middle ear.     

A continuous colorimetric assay for rhinovirus-14 3C protease using peptide p-nitroanilides as substrates

Primary salivary gland lymphomas are almost always of B lineage, with most being represented by low grade B-cell lymphoma of mucosa-associated lymphoid tissue. This study characterizes the rare non-B-cell lymphomas of the salivary gland based on an analysis of six cases. All patients were men, with a mean age of 53.5 years. They presented with submandibular or parotid mass, which on histological examination showed extensive interstitial infiltration by small, medium-sized, or large lymphoid cells. There was prominent invasion and expansion of the ducts and acini in five cases. Angioinvasion was evident in two cases. Three cases were of T lineage and were CD56 negative; one of these cases expressed CD30. Three cases showed an immunophenotype of CD2+ CD3(f)- CD3(p)+ CD56+, consistent with T/natural killer (NK) cell lymphoma. In situ hybridization for Epstein-Barr virus (EBV)-encoded early nuclear RNA (EBER) showed positive reaction exclusively in the three CD56+ cases. Clonal T-cell populations were shown in two CD56-negative cases by polymerase chain reaction on paraffin sections using primers for the T-cell-receptor (TCR) gamma-chain gene, but not in the other four cases (the three CD56+ cases and one CD56- case). Four patients (two CD56+ and two CD56-) died within 3 years, and two were disease free at 4 and 1.5 years, respectively. This study shows that salivary gland T- or T/NK-cell lymphomas cannot be reliably distinguished from B-cell lymphomas on morphological grounds alone, because both can show prominent lymphoepithelial lesions. It appears that T/NK-cell lymphomas, which are often extranodal in localization and strongly associated with Epstein-Barr virus (EBV), show a predilection to involve the salivary glands as well.     

Schistosomiasis around Siavonga, on the shores of Lake Kariba, Zambia

The DNA profile of blast cells was assayed in 61 children with acute leukemias (51 patients) and non-Hodgkins lymphomas (NHL--10 patients). The value of S phase (synthesis of DNA) and G2M phase (mitotic stage) was compared between the subtypes of acute leukemia and lymphoma based on blast cell phenotype. In acute lymphoblastic leukemia (ALL) the lowest S phase of blast cells was seen in null-ALL subtype, the highest in T-ALL. In non-lymphoblastic leukemia (ANLL) the value of S phase was below S phase observed in ALL. B cell NHL showed higher S phase as compared to T-lymphocyte derived NHL cells. Aneuploidy was noted as hyperdiploidy (8 cases), hypodiploidy (4 cases) and two leukemia cell lines (3 ALL patients). The DNA profile as marker of proliferative activity of blastic cells provides an important information associated with the prognosis of patient.     

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.     

Differential expression of BCL-6, CD138/syndecan-1, and Epstein-Barr virus-encoded latent membrane protein-1 identifies distinct histogenetic subsets of acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas

This study was aimed at defining the histogenesis of the pathologic spectrum of acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas (AIDS-NHL), including AIDS-related small noncleaved cell lymphoma (AIDS-SNCCL), AIDS-related large noncleaved cell lymphoma (AIDS-LNCCL), AIDS-related large cell immunoblastic lymphoma plasmacytoid (AIDS-IBLP), and AIDS-related primary effusion lymphoma (AIDS-PEL). Forty-six cases of AIDS-NHL were investigated for the expression pattern of BCL-6, a protein specifically expressed by germinal center (GC) B-cells, and CD138/syndecan-1 (syn-1), a marker of post-GC B-cell differentiation. Expression of BCL-6 and syn-1 segregated two major phenotypic patterns among AIDS-NHL: (1) the BCL-6+/syn-1- pattern associated with AIDS-SNCCL and AIDS-LNCCL; (2) the BCL-6-/syn-1+ pattern associated with AIDS-IBLP and AIDS-PEL. Among systemic AIDS-NHL infected by Epstein-Barr virus (EBV), expression of the EBV-encoded latent membrane protein-1 (LMP-1) preferentially associated with the BCL-6-/syn-1+ profile. Analysis of nonneoplastic lymph nodes showed that the two phenotypic patterns detected in AIDS-NHL correspond to physiologic stages of B-cell development, i.e., GC B-cells (BCL-6+/syn-1-) and preterminally differentiated post-GC B-cells (BCL-6-/syn-1+). Thus, BCL-6+/syn-1- AIDS-NHL reflects a GC stage of differentiation, whereas AIDS-NHL which are BCL-6-/syn-1+, and LMP-1+ when infected by EBV, derive from B cells that have entered post-GC plasmacell differentiation. These findings are relevant for the pathogenesis and differential diagnosis of AIDS-NHL.     

A novel adult T cell leukemia-derived cell line (SALT-3) susceptible to human immunodeficiency virus type 1 infection

A novel human T cell line (SALT-3) was established from the pleural effusion of a patient with adult T cell leukemia (ATL) of lymphoma type. SALT-3 showed atypical T cell markers such as CD1-CD2-CD3-CD4+CD5+CD7+CD8-CD19-CD20-CD25+HLA-DR+. T cell receptor alpha/beta and gamma/delta were undetectable. Human T cell lymphotropic virus type 1 (HTLV-I) particles were seen on SALT-3 cells by electron microscopic analysis. HTLV-I gag p19, proviral DNA and mRNA of HTLV-I genes were also detected in the cells. Chromosome analysis showed abnormal karyotypes as 47, XY, partial trisomy of No.3 chromosome, and trisomy of No. 7 chromosome. Furthermore, SALT-3 were susceptible to the infection of human immunodeficiency virus type 1 (HIV-1) and the cells were rapidly killed after HIV-1 infection. This newly established HTLV-I-infected human T cell line would be a useful tool to study biological activities of atypical type of ATL cells and to examine the cytotoxic effects of HIV-1 and it's modulators.     

Cloning of BY55, a novel Ig superfamily member expressed on NK cells, CTL, and intestinal intraepithelial lymphocytes

Expression of the BY55 protein has been shown to be tightly associated with NK and CD8+ T lymphocytes with cytolytic effector activity. To determine the function of this protein, we molecularly cloned BY55 cDNA. The cDNA sequence predicts a cysteine-rich, glycosylphosphatidylinositol-anchored protein of 181 amino acids with a single Ig-like domain weakly homologous to killer inhibitory receptors. Reduction and carboxyamidomethylation of immunoprecipitated BY55 gave a band of 27 kDa, whereas reduction alone led to an 80-kDa species, suggesting that BY55 is a tightly disulfide-linked multimer. RNA blot analysis revealed BY55 mRNAs of 1.5 and 1.6 kb whose expression was highly restricted to NK and T cells. BY55 was expressed on the CD56dim, CD16+ subset of NK cells, which have high cytolytic activity, but was not expressed and was not induced on the CD56bright, CD16-subset of NK cells, a subset with high proliferative, but low cytolytic, capacity. In human tissues, BY55 mRNA was expressed only in spleen, PBL, and small intestine (in gut lymphocytes). BY55 was expressed on all intestinal intraepithelial lymphocytes, which were predominantly CD3+TCRalpha/beta+CD4-CD8+CD11b+CD28-CD45RO+C D56-CD101+CD103+ (alphaEbeta7 integrin). In addition, BY55 was expressed on most CD8+CD28- peripheral blood T cells. These phenotypic relationships suggest that CD8+CD28+ precursor CTL may terminally differentiate into CD8+CD28-BY55+ effector CTL and that some of the peripheral blood CD8+CD28- subset may represent recirculation from mucosal epithelial immune sites.