A child case of CD34+, CD33-, HLA-DR-, CD7+, CD56+ stem cell leukemia with thymic involvement

It has been reported that the CD56+/CD7+/CD3- phenotype of natural killer (NK) cells develop from the CD34+/HLA-DR- bone marrow (BM) mononuclear cell population in long-term BM culture (LTBMC). An HLA-DR-/CD33+/CD56+/CD16- myeloid/natural killer cell acute leukemia has been described. We report here a 7-year-old boy who developed stem cell acute leukemia with superior vena cava syndrome secondary to thymic involvement. Surface marker analyses revealed that the leukemia cells showed CD34+/HLA-DR-/CD33-/CD7+/CD56+ phenotype. When stimulated with phorbol ester in vitro the leukemic cells morphologically differentiated to myeloid cells developing CD13, CD15 and CD56 antigens. Our results suggest that CD34+/HLA-DR-/CD7+/CD56+ stem cell leukemia may arise from transformation of a pluripotent precursor cell, which could differentiate to both myeloid and NK cell lineages.     

Subcutaneous panniculitis-like T-cell lymphoma: further evidence for a distinct neoplasm originating from large granular lymphocytes of T/NK phenotype

We report the case of a 20 year-old caucasian woman who presented a primary subcutaneous panniculitis-like T-cell lymphoma (SPTCL) as an invasive tumor of the chest wall. Herein, the neoplastic cells were found to express a CD3+CD8+ phenotype but also displayed variably the natural killer (NK)-associated antigens CD56 and CD57 as well as granzyme B. On cytological examination, these cells showed a large granular lymphocyte (LGL)-like morphology with presence of azurophilic granules in their cytoplasm. Electron dense and membrane bound granules like those found in cytotoxic T lymphocytes (CTL) were also demonstrated by electron microscopy. Neither rearrangement of the T-cell receptor subunits nor Epstein-Barr virus (EBV) genome was observed at the molecular level. The LGL-like features of the neoplastic cells found in this case and the presence of NK-associated antigens provide additional support to the cytotoxic derivation of most SPTCL.     

Natural T cells in the human liver: cytotoxic lymphocytes with dual T cell and natural killer cell phenotype and function are phenotypically heterogenous and include Valpha24-JalphaQ and gammadelta T cell receptor bearing cells

The adult liver contains lymphocytes with a unique phenotypic distribution compared to blood and other organs. We have characterized a human lymphocyte population that exhibits dual T cell and natural killer (NK) cell phenotype and function, denoted natural T (NT) cells, in nine normal adult liver specimens. Flow cytometry revealed that up to 55% (mean 27%) of hepatic (but <6% of peripheral) CD3+ lymphocytes expressed CD56, CD161 and/or one or more of the killer inhibitory receptors (KIR) p58.1, p58.2, p70 and CD94. NK function was attributed to the CD3+CD56+ cells by the demonstration that hepatic, but not peripheral, CD3+ lymphocytes could be induced to lyse NK-sensitive K562 target cells, while CD56- cells from both compartments could not. Three color flow cytometric analysis of fresh hepatic cells indicated that CD3+CD56+ NT cells can be either CD8+, CD4+ or CD4 CD8-, they express alphabeta or gammadelta T cell receptors (TCR) and CD161 and KIRs, but rarely CD16. Hepatic NT cells predominantly express the mature/activated CD45RO and CD56dim phenotypes. Analysis of mRNA production by isolated NT cells indicated a preferential usage of the invariant CD1-restricted Valpha24-JalphaQ TCR. The presence of such large numbers of chronically activated NT cells provides compelling evidence that the liver has unique immunoregulatory functions.     

Epidermodysplasia verruciformis accompanied by familial large granular lymphocytosis and a decrease in T lymphocytes

A 40-year-old man with epidermodysplasia verruciformis showed a decrease in peripheral blood T cells and abnormal expansion of large granular lymphocytes, accompanied by increased natural killer cell activity. Surface marker analysis of his large granular lymphocytes demonstrated that the subset, CD 57+ and CD 16+, had increased. His father, who had no skin lesions of epidermodysplasia verruciformis, displayed similar blood changes and his brother showed a decrease in T cells and a slight increase in CD 16+ natural killer cells, whereas his mother revealed only a slight decrease in T cells. Our present study indicates that epidermodysplasia verruciformis might be associated with hereditary abnormal expansion of large granular lymphocytes and a decrease in T cells.     

Genealogy reconstruction from short tandem repeat genotypes in an Amazonian population

We report seven cases of particular cutaneous tumors selected from the register of the French Study Group on Cutaneous Lymphomas. The patients (three men, four women) were aged 37-86 years. They initially presented with cutaneous nodules or papules. Three cases presented with regional lymph nodes. Stagings were negative, except for one patient with bone marrow involvement. Histological features were relevant with pleomorphic medium T-cell lymphoma, but these cells exhibited a distinguishing phenotype. They were positive for CD4, CD56, and also CD45, CD43, and HLA-DR. All other T-cell and B-cell markers were negative. The myelomonocytic markers (CD13, CD14, CD15, CD33, CD117, myeloperoxidase, and lysozyme) were negative excepted CD68, which was clearly positive in four cases and weakly in two cases. Others natural killer cell markers (CD16, CD57, TiA1, granzyme B), TdT, and CD34 were negative. Polymerase chain reaction studies did not detect any B or T clonal rearrangement. The cytogenetic studies, performed in five cases, showed a del(5q) in two cases. All patients were treated successfully by polychemotherapy, but relapsed quickly in the skin, between 4 and 28 months. Five patients developed bone marrow involvement, with leukemia in three cases, and they died in 5-27 months. One patient died at 17 months with skin progression. The seventh patient is alive at 33 months, with cutaneous progression. The origin of these cells is unclear. Despite expression of CD4 or CD56, we failed to demonstrate a T-cell, natural killer cell origin. However, CD4 and CD56 are not specific for T or natural killer lineages. Although these two markers are also known to be expressed by monocytic cells, classic myeloid antigens were negative. These seven cases, together with other rare similar cases already reported, seem to represent a distinct entity likely developed from hematological precursor cells.     

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.     

CD56+ putative natural killer cell lymphomas: production of cytolytic effectors and related proteins mediating tumor cell apoptosis?

Apoptosis is a regulated form of cell death that may be triggered by natural killer (NK) or cytotoxic T cells, which effect target cell lysis by cytolytic effector and related proteins through complex intracellular signals. This study was aimed to investigate whether there is selective expression of these cytolytic markers in the putative NK-cell lymphomas and whether there is correlation with zonal tumor cell death in these tumors. Expression of the cytolytic effectors perforin, granzyme B9, and the granule membrane protein TIA1 were examined in 24 putative NK-cell lymphomas, 18 postthymic T-cell lymphomas (one case CD8+ CD56+ and three anaplastic large cell lymphomas (ALCL), three T-lymphoblastic lymphomas, and 20 B-cell lymphomas. Nineteen (79%) putative NK-cell lymphomas expressed perforin, and all 24 cases expressed granzyme B9 and TIA1. The only CD8+ CD56+ postthymic T-cell lymphoma also expressed all three cytolytic markers, two CD8- ALCL expressed TIA1; other postthymic T-cell, T-lymphoblastic, and B-cell lymphomas were consistently negative. There was strong correlation between percentage perforin-positive cells and zonal tumor cell death. Angioinvasion, in contrast, was present only in a proportion (37%) of these lymphomas despite the frequent presence of zonal tumor cell death (71%). We propose that cytolytic effector and related proteins produced by putative NK and some CD8+ CD56+ postthymic T-cell lymphomas, probably in conjunction with other mechanisms, may effect massive tumor cell apoptosis. The frequent expression of cytolytic effector markers in the CD2+ surface CD3- CD56+ putative NK-cell lymphomas lends further support to their probable NK cell origin.     

CD56-positive cutaneous lymphoma: a poorly recognized entity in the spectrum of primary cutaneous disease

CD56-positive (CD56+) lymphomas, characterized by the expression of the neural cell adhesion molecule on pathological lymphocytes, share a frequent extranodal involvement and a generally aggressive course. Five CD3- CD56+ lymphoma patients presenting with nodular lesions were identified among 180 immunophenotyped cutaneous lymphomas. All the patients were men, with ages ranging from 55 to 78 years. After staging, two patients were diagnosed as having primary cutaneous lymphomas; the remaining three had the secondary cutaneous type. The clinical course was aggressive and four patients died within 8 months from diagnosis. The remaining patient is still alive after a 17-month follow-up. The histological diagnosis was immunoblastic lymphoma in two patients, and medium and large cell pleomorphic lymphoma in three. The angiocentric infiltrate was located mainly in the dermis; azurophilic granules were present in three of the five patients. Immunogenotypic analyses suggested the natural killer cell origin of these neoplasias: all cases exhibited a CD56+ CD3- CD5- T-cell receptor (TCR) silent phenotype, and Southern blot analysis showed a germline configuration of the TCR beta-chain gene.     

Immunotherapy with donor leukocyte infusions for patients with relapsed acute myeloid leukemia following partially mismatched related donor bone marrow transplantation

Donor leukocyte infusions (DLI) were used to treat 2 patients with AML who relapsed within 4 months of treatment with partially mismatched related donor (PMRD) BMT representing 1-2 HLA-mismatches. No other form of cytoreductive therapy was given to these patients. Both patients developed GVHD (grade II-III) following DLI requiring steroid therapy. One of these patients went into complete remission following development of GVHD and immunophenotypic analysis of peripheral blood showed increased numbers of CD3+/CD8+ T cells, CD56+/CD8+ lymphokine activated killer (LAK) cells and CD16+/CD56+ natural killer (NK) cells expressing intermediate affinity IL-2 receptor P75. Unfortunately, the response was of short duration and the patient relapsed 8 weeks later ultimately resulting in death. The second patient did not show any response to DLI and died of progressive leukemia in conjunction with active GVHD. We conclude that DLI from PMRD carries a high risk for the development of GVHD and may have an anti-leukemia effect for relapsed AML. The anti-leukemic effect from PMRD DLI may be mediated by cytotoxic T lymphocytes, LAK cells and NK cells.     

Differential expression of natural killer cell markers: human versus baboon

The use of baboons as a model for the study of allo- and xenotransplantation has become increasingly important, but there are few studies on the basic immunological responses in baboons that might be relevant for a rejection reaction. In present study, the cell-surface phenotype, cytokine-induced activation and growth, and cytotoxicity of baboon and human natural killer (NK) and lymphokine-activated killer (LAK) cells were compared. A panel of murine monoclonal antibodies specific for human cell-surface markers expressed on lymphocytes was used to compare relevant baboon and human peripheral blood lymphocytes (PBL). Baboon PBL were 52.1+/-2.9% CD8+, 18.5+/-2.2% CD16+, 3.0+/-0.5% CD25+, and 5.5+/-1.8% CD69+. The corresponding proportions in humans were 23.8+/-7.1%, 12.8+/-3.2%, 4.5+/-1.0%, and 2.3+/-1.1%. In contrast to human PBL, less than 1% of baboon lymphocytes expressed CD56, CD57, and CD122 (interleukin [IL]-2Rbeta). Baboon lymphocytes showed NK cytotoxic activity against the human K562 and CEM cell lines, which was comparable to human NK activity. Depletion of baboon CD16+ or CD8+ cells led to dramatic decreases in NK cytotoxicity, and removal of both subsets completely abrogated NK activity. Incubation of baboon lymphocytes with human recombinant IL-2 for 1 week led to the appearance of CD56+ cells (11.3+/-2.8%). Most of the baboon CD56+ cells induced in culture were in S and G2 phases of cell cycle. Both baboon and human IL-2-activated lymphocytes were highly cytotoxic against the human LAK-sensitive cell line Daudi. Depletion of baboon CD8+ but not CD56+ cells significantly decreased LAK activity. These studies revealed differences in the NK system of humans and baboons that should be taken into consideration when analyzing immune responses to allo- and xenotransplantation in baboons.     

Aggressive NK cell lymphoma preceded by a ten year history of neutropenia associated with large granular lymphocyte lymphocytosis

We report a case of aggressive natural killer (NK) cell lymphoma in an 82 year old man who first presented 10 years earlier with neutropenia in association with a large granular lymphocyte (LGL) lymphocytosis. The diagnosis of NK cell lymphoma was made on the basis of morphological and immunological characteristics (CD3-CD56+) found on skin biopsy of one of multiple skin nodules which subsequently developed in association with splenomegaly, thrombocytopenia and continuing neutropenia. In addition there was BM infiltration and a cytogenetic abnormality [add(6)(p25)] was detected. Combination chemotherapy led to an initial clinical response but a relapse occurred shortly afterwards and the patient died 8 months later from infection whilst neutropenic following re-introduction of chemotherapy. Previously reported cases of aggressive NK cell lymphoma have shown a young male predominance with a rapidly progressive clinical course and without evidence of a preceding chronic phase of LGL lymphocytosis and neutropenia.     

Rationalizing infection control in the dental office

We performed a prospective study in 17 consecutive patients following Autologous bone marrow (BM) or rhG-CSF primed peripheral blood item cell (PBSC) transplantation, with the objective of comparing immune recovery between both procedures and to evaluate results in rhG-CSF mobilized peripheral blood stem cell transplantation (PBSCT). Kinetics of immune reconstitution showed differences, with a faster recovery of CD3+ and CD8+ T cells, and a more rapid and sustained recovery of CD8+/-/CD56+ natural killer (NK) cells in the PBCSCT group. Autologous bone marrow transplantation (ABMT) was associated with a improved reconstitution of the CD19+/CD5+/-subpopulation. Moreover, rhG-CSF mobilized PBSCT generated a greater recovery of CD8+/-/CD56+ cells than previous data concerning transplantation with peripheral blood (PB) progenitors collected after myelosuppressive chemotherapy or myelosuppressive therapy plus rhG-CSF. Our results show differences in the rate and pattern of B and T lymphocytes reconstitution after ABMT and PBSCT. Additionally, we state an enhancement of CD56+ cells in patients undergoing PBSCT mobilized solely using rhG-CSF.     

Epstein-Barr virus associated natural killer cell leukemia: report of an autopsy case

A 20-year-old female was admitted because of high fever, hepatosplenomegaly, severe hepatic dysfunction and coagulopathy. Peripheral blood showed pancytopenia and granular lymphocytes bearing the natural killer cell phenotype (CD2+CD3-CD16+CD56+CD57-TCR alpha beta-TCR gamma delta-) constituted 97% of leucocytes. Southern blot analysis of DNA obtained from peripheral blood mononuclear cells showed germ-line configuration of TCR beta, gamma and delta chain genes. EBV-DNA was detected in a single episomal form by using EBV-terminal repeat probe. Bone marrow findings were consistent with hemophagocytic syndrome and administration of VP-16 was effective transiently. After ten months she died from massive gastrointestinal bleeding. An in situ hybridization study identified EBV-RNA (EBER-1) in atypical lymphocytes infiltrating bone marrow, spleen and lymph nodes. Sections of liver showed steatosis and infiltration of T cells (CD3+ and EBER-1-negative) in the portal areas and few atypical lymphocytes in sinusoids. The patients developed an EBV-associated clonal proliferation of natural killer (NK) cells, but the clinical features were suggestive of chronic active EBV infection or virus-associated hemophagocytic syndrome (VAHS) rather than leukemia. Bone marrow transplantation for NK cell leukemia is an issue to be discussed.     

Human natural killer cell committed thymocytes and their relation to the T cell lineage

Recent studies have demonstrated that mature natural killer (NK) cells can be grown from human triple negative (TN; CD3-, CD4-, CD8-) thymocytes, suggesting that a common NK/T cell precursor exists within the thymus that can give rise to both NK cells and T cells under appropriate conditions. In the present study, we have investigated human fetal and postnatal thymus to determine whether NK cells and their precursors exist within this tissue and whether NK cells can be distinguished from T cell progenitors. Based on the surface expression of CD56 (an NK cell-associated antigen) and CD5 (a T cell-associated antigen), three phenotypically distinctive populations of TN thymocytes were identified. CD56+, CD5-; CD56-, CD5-, and CD56-, CD5+. The CD56+, CD5- population of TN thymocytes, although displaying a low cytolytic function against NK sensitive tumor cell targets, were similar in antigenic phenotype to fetal liver NK cells, gave rise to NK cell clones, and were unable to generate T cells in mouse fetal thymic organ cultures (mFTOC). This population of thymocytes represents a relatively mature population of lineage-committed NK cells. The CD56-, CD5- population of TN thymocytes were similar to thymic NK cells in antigenic phenotype and NK cell clonogenic potential. Clones derived from this population of TN thymocytes acquired CD56 surface expression and NK cell cytolytic function. CD56-, CD5- TN thymocytes thus contain a novel population of NK cell-committed precursors. The CD56-, CD5- population of TN thymocytes also contains a small percentage of CD34+ cells, which demonstrate no in vitro clonogenic potential, but possess T cell reconstituting capabilities in mFTOC. The majority of TN thymocytes do not express CD56, but coexpress CD34 and CD5. These CD56-, CD5+, CD34+ cells demonstrate no NK or T cell clonogenic potential, but are extremely efficient in repopulating mFTOC and differentiating into CD3+, CD4+, CD8+ T cells. The results of this investigation have identified NK cells and NK cell precursors in the human thymus and have shown that these cell types are unable to differentiate along the T cell lineage pathway. Thus, while a common NK/T cell progenitor likely exists, once committed to the NK cell lineage these cells no longer have the capacity to develop along the T cell developmental pathway.     

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.     

Bcl-2 is expressed in human natural killer cells and is regulated by interleukin-2

Bcl-2 is a major anti-apoptotic protein expressed in many normal and malignant cells. Recently, low to absent expression was reported in human natural killer (NK) cells cultured in serum-free media which could be induced with stem cell factor. We investigated the expression of bcl-2 protein of NK cells in normal blood donors and compared the bcl-2 expression in CD56+ NK cells with CD3+ T cells. To determine bcl-2 reactivity, a three-color flow-cytometric technique was used. CD56+ CD3- NK cells had an average bcl-2 expression of 83% compared with CD3+ T cells. CD56 and CD3 double positive T cells had an average content of 111% compared with all peripheral CD3+ T lymphocytes. When peripheral mononuclear cells were cultured with interleukin-2 (IL-2), bcl-2 could be upregulated by IL-2 in all cell populations studied. The induction of bcl-2 in these cell populations paralleled the induction in CD56- T lymphocytes cultured under identical conditions. The induction of bcl-2 by IL-2 was confirmed by Western blotting. The maximum induction of bcl-2 by IL-2 was observed at an IL-2 dose of 100-1,000 U/ml. Our data confirm the anti-apoptotic protein bcl-2 as an activation- or proliferation-associated marker of normal NK cells which can be induced by IL-2.     

Characterization of the neurochemical effects of N-[2-(1-azabicyclo[3,3,0]octan-5-yl)ethyl]2-nitroaniline fumarate (SK-946) as a cognition activator

BACKGROUND: This study characterized the phenotypic subsets of isolated gastric lymphocytes and the cellular immune response in cultured gastric biopsy specimens. METHODS: Endoscopy specimens from 40 Helicobacter pylori-positive and 40 H. pylori-negative patients were studied. a) Isolated gastric lymphocytes were analysed for CD4+, CD8+ T-lymphocyte subsets, activated T cells, and natural killer cells on a fluorescence-activated cell sorter, using monoclonal antibodies. b) The supernatant of cultured gastric biopsy specimens were assayed for interleukin (IL)-2, IL-4, and IL-6 levels. RESULTS: In H. pylori-positive patients there was (a) a decrease in CD4+/CD8+ T cells, no change in activated T cells, and an increase in natural killer cells, and (b) no change in IL-2 levels and a significant increase in IL-4 and IL-6 levels. CONCLUSIONS: There is an increase in CD8+ lymphocytes and natural killer cells, and the observed increase in IL-4 and IL-6 might be important in H. pylori-associated gastritis.     

Later development of Fas ligand-mediated cytotoxicity as compared with granule-mediated cytotoxicity during the maturation of natural killer cells

We classified CD56+ CD3- natural killer (NK) cells into CD2- CD56dim (CD2- NK), CD2+ CD56dim (CD2+ NK) and CD2+ CD56bright populations, and investigated mainly functional differences between the former two populations. CD2- and CD2+ NK cells were the same in their morphology and several surface molecules except for CD2. The percentages of CD2- NK cells in total NK cells were higher in the cord blood and marrow than in the peripheral blood of adults or children. Freshly isolated CD2- NK cells had CD2 in the cytoplasm, and gradually expressed it on the surface upon incubation with interleukin-2 (IL-2). These results demonstrated that CD2 is an antigen which appears on the surface during the maturation of NK cells. The granule-mediated cytotoxicities, which are mainly performed by the perforin molecule, of CD2+ NK cells against K562 and Daudi cells were higher than those of CD2- NK cells, and they were inhibited to the levels of CD2- NK cells by the addition of a blocking anti-CD2 monoclonal antibody (mAb). Fas ligand (FasL) mRNA was expressed in freshly isolated CD2+ NK cells but not in the CD2- NK cells. Neither freshly isolated NK populations showed FasL-mediated cytotoxicity, and only CD2+ NK cells lysed Fas-transfected targets after the 24-hr incubation with IL-2. Based on these results, CD2- NK cells have already developed granule-mediated cytotoxicity equal to that of CD2+ NK cells except for the CD2-associated activity, but they, unlike CD2+ NK cells, totally lack FasL-mediated cytotoxicity. These findings suggest that FasL-mediated cytotoxicity may be acquired at more mature stages of NK-cell maturation than granule-mediated cytotoxicity.     

Identification of spherical virus particles in digitized images of entire electron micrographs

Interferon-gamma (IFN-gamma) has the most potent immunomodulatory activity of all the interferons. This phase II-B study was performed to define time- and dose-dependent immunomodulatory effects mediated by IFN-gamma in a subset of patients with melanoma treated in the dose-seeking therapeutic trial conducted by the Eastern Cooperative Oncology Group E4687 (13). The effects of IFN-gamma (Genentech, San Francisco, CA) were evaluated for phenotype and function of peripheral blood lymphocytes obtained twice prestudy, and on days 2, 9, and 29 of IFN-gamma therapy for 50 patients. Early significant increases in CD4/CD8 ratio (p = 0.001) were noted, largely due to a rise in CD4+ and fall in CD8+ T-cell populations sustained through day 29 at only the lowest dosage. Increased natural killer cell (NK) activity (p = 0.001 on day 9; p = 0.01 on day 29) was accompanied by durable increases in circulating activated NK cells (CD56+DR+% p = 0.001, day 9; p = 0.001, day 29). After initial depression of CD56+ and CD16+ cells on day 2, the total percent of CD56+ and CD16+ cells increased significantly by day 29. Increases in NK cell activity were maximal at doses > or =0.1 mg. Monocyte CD14+ expression of DQ+ rose early (p = 0.011 and 0.001 on days 2 and 9), accompanied by elevation in CD14+DR+ cells that was less significant. Immunomodulatory effects of IFN-gamma reported in this trial have major implications for interpretation of past and current clinical trials, and the design of future trials. This is the first trial in which IFN-gamma has been shown to have significant effects on the T-cell compartment of the immune system.     

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.