Biomedical subjects

C Morimoto

Publications and source records attributed to C Morimoto.

At least 181 records · Page 10Linked to original sources

PubMed1989

Response patterns of purified myeloma cells to hematopoietic growth factors.

Tumor cells were isolated from the bone marrow of seven patients with multiple myeloma and from the peripheral blood of three patients with plasma cell leukemia using Ficoll-Hypaque (FH) density sedimentation followed by immune rosette depletion of T, myeloid, monocytoid, and natural killer (NK) cells. Enrichment to greater than or equal to 93% plasma cells was confirmed with Wright's-Giemsa staining, with intracytoplasmic immunoglobulin staining, and with staining using monoclonal antibodies (MoAbs) directed at B, T, myeloid, monocytoid, and myeloma antigens in indirect immunofluorescence assays. Myeloma cells neither proliferated nor secreted Ig in response to G/M-CSF, G-CSF, M-CSF, interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), or interleukin-4 (IL-4). Significant proliferation (SI greater than or equal to 3.0) was induced by interleukin-6 (IL-6) in six of ten patients (SI of 31 and 43 in two cases); and to interleukin-3 (IL-3) and interleukin-5 (IL-5), independently, in two patients each. Peak proliferation to IL-5 or IL-6 and to IL-3 occurred in cells pulsed with 3[H] thymidine at 24 and 48 hours, respectively; and proliferation to combinations of factors did not exceed that noted to IL-6 alone; Ig secretion was not documented under any culture conditions. Three myeloma-derived cell lines similarly studied demonstrated variable responses. The heterogeneity in the in vitro responses of myeloma cells and derived cell lines to exogenous growth factors enhances our understanding of abnormal plasma cell growth and may yield insight into the pathophysiology of plasma cell dyscrasias.

Antigens, Surface↗

PubMed1989

A cytotoxic T lymphocyte inhibits acquired immunodeficiency syndrome virus replication in peripheral blood lymphocytes.

CD8+ (suppressor/cytotoxic) lymphocytes block replication of HIV-1 or the simian immunodeficiency virus of macaques (SIVmac) in PBL of infected individuals. We now show that these CD8+ lymphocytes undergo clonal expansion in vivo after AIDS virus infection of the individual, suggesting they may be antigen-specific T cells. These CD8+ cells block replication of virus in autologous but not MHC class I-mismatched PBL. The inhibitory lymphocytes express the integrin family molecule 4B4 and the CTL-associated S6F1 epitope of LFA-1. Finally, physical contact is required for the CD8+ lymphocyte-mediated inhibition of AIDS virus replication, since this inhibitory function is blocked by anti-LFA-1 and anti-CD8 mAbs. These studies suggest that the cell that inhibits AIDS virus replication in PBL of infected individuals is a CTL.

Animals↗

PubMed1989

Decrease of suppressor inducer (CD4+2H4+) T cells in multiple sclerosis cerebrospinal fluid.

T-lymphocytes in the cerebrospinal fluid of patients with multiple sclerosis are predominantly CD4+ (inducer) as opposed to CD8+ (suppressor/cytotoxic) T cells. The CD4+ lymphocytes can be subdivided into populations that express high densities of the CDw29 (4B4) determinant and have helper inducer function or express high densities of CD45R (2H4) determinant and have suppressor inducer function. In the present study, we characterized the nature of these CD4+ T cells in the cerebrospinal fluid of patients with multiple sclerosis by performing flow cytometric analysis on paired samples of blood and cerebrospinal fluid. There were significantly lower percentages of CD4+2H4+ T cells in the cerebrospinal fluid than in the peripheral blood (p = 0.001, paired t test). In contrast, there were increased percentages of helper inducer (CD4+4B4+) T cells in the cerebrospinal fluid (p = 0.001, paired t test), compared with the peripheral blood. Analysis of subjects with other inflammatory disorders of the central nervous system did not show significant decreases in CD4+2H4+ T cells in cerebrospinal fluid, though in some, decreases were also observed. These results indicate that the CD4+ T cells in the cerebrospinal fluid of patients with multiple sclerosis are predominantly helper inducer, as opposed to suppressor inducer T cells, and that the relative decrease of suppressor inducer cells in the peripheral blood of multiple sclerosis patients is not due to their migration to the cerebrospinal fluid. Furthermore, the increased numbers of helper inducer cells in the cerebrospinal fluid may contribute to local autoimmune processes in the central nervous system compartment of multiple sclerosis patients.

Humans↗

PubMed1989

Antilymphocyte antibodies against CD4+2H4+ cell populations in patients with systemic lupus erythematosus.

In previous studies, we demonstrated that patients with active systemic lupus erythematosus (SLE) had significantly decreased percentages of circulating CD4+2H4+ suppressor/inducer cells. The decrease in this T cell subset was most frequent and most marked in patients with active SLE and renal disease. In the present study, we attempted to determine whether SLE patients had plasma antilymphocyte antibodies preferentially reactive with the CD4+2H4+ subset. We found that many SLE patients did have these specifically reactive antibodies. Furthermore, the presence of antilymphocyte antibodies reactive with CD4+2H4+ cells correlated with disease activity in these patients. Also, in vitro functional studies revealed that suppressor/inducer function was eliminated in the pokeweed mitogen-driven IgG synthesis system after the treatment of CD4 cells with patient plasma antilymphocyte antibodies and complement. These results suggest that antilymphocyte antibodies play a role in the elimination of CD4+2H4+ cells in patients with active SLE.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1989

Functional characterization of the CD45R (2H4) molecule on CD8 (T8) cells in the autologous mixed lymphocyte reaction system.

In the present study, we have investigated the molecular basis for the immunoregulatory function of CD8 cells after autologous mixed lymphocyte reaction (AMLR) activation. We demonstrated that the CD8+CD45R+, but not the CD8+CD45R- subset of cells effected suppression following AMLR activation. In contrast, cytotoxic activity against alloantigens resided in both the CD8+CD45R+ and CD8+CD45R- subsets of cells. Biochemical analysis showed that on CD8 cells, the 220-kDa isoform of the LCA/T200 antigen family was better represented than the 200-kDa isoform, when compared to CD4 cells. The density of the CD45R antigen increased on CD8 cells following activation in AMLR and treatment of AMLR-activated CD8 cells with either anti-CD45R antibody or anti-CD3 antibody abolished the suppressor function of these cells. In contrast, treatment of AMLR-activated CD4 cells with anti-CD45R, but not anti-CD3 antibody, abolished the suppressor/inducer function of these cells. The results suggest that the CD45R antigen as well as CD3 T cell receptor complex have an important role in the suppressor function of AMLR-activated CD8 cells.

Antigen-Antibody Reactions↗

PubMed1989

Amplification of suppressor inducer pathway with monoclonal antibody, anti-2H4, identifying a novel epitope of the common leukocyte antigen/T200 antigen.

The 2H4 antigen, comprised of a 200/220-kDa glycoprotein of the leukocyte common antigen (LCA) family, is expressed on a suppressor inducer, but not a helper inducer subset of T4 cells. Earlier studies have demonstrated that the T4+2H4+ subset of cells maximally responded to the AMLR and this molecule has an important role in generated suppressor signals in AMLR/Con A-activated T cell systems. In the present study, we examined the effect of a series of monoclonal antibodies including anti-2H4 antibody on the initial activation of T4 cells in response to self-Ia antigens. We found that the addition of anti-2H4 antibody resulted in an augmentation of the proliferative response of T4 cells in AMLR, whereas other antibodies reactive with LCA/T200 antigens lacked this ability. Furthermore, anti-2H4 antibody enhanced both IL-2 production and IL-2R expression in this AMLR system. This enhancing effect was inhibited by anti-T3 antibody. Moreover, the suppressor inducer function of AMLR T4 cells was enhanced with anti-2H4 antibody by increasing the number of 2H4+ cells with high antigen density. Taken together, these results suggest that the 2H4 antigen may serve as an accessory structure for enhancing the activation of the T4+2H4+ suppressor inducer subset at initiation of cell triggering.

Antibodies, Monoclonal↗

PubMed1989

Structural characterization of CD6: properties of two distinct epitopes involved in T cell activation.

Studies from our laboratory have shown that anti-T12, a mAb which recognizes CD6, is a macrophage-dependent mitogen for human T cells and can augment T cell autoreactivity in vitro. To obtain additional information regarding the potential biological role of CD6 we sought to further characterize its biochemical properties. The CD6 molecule on 125I-surface-labeled T cells and by Western blot analysis was a monomer of mol. wt 130,000 under reducing conditions and mol. wt 117,000 under non-reducing conditions, suggesting the presence of intrachain disulfide bonds. The polypeptide contains a protease sensitive site. In activated T cells, the protein was serine phosphorylated. Analysis of biosynthetically labeled CD6 in the presence of tunicamycin revealed a reduction in mol. wt from 130,000 to 100,000, indicating that the polypeptide is extensively N-glycosylated. The mAb, anti-2H1, had been shown to activate T cells in combination with PMA or the anti-T11(3) mAb but, unlike anti-T12, not in the presence of macrophages alone. The present studies demonstrate by sequential immunoprecipitation that these two mAbs recognize the same polypeptide. However, Western blot analysis and indirect immunofluorescence cross-blocking studies demonstrate that the two mAbs recognize different determinants on CD6. Anti-T12 recognizes an epitope that is present only under non-reducing/non-denaturing conditions, while anti-2H1 recognizes an epitope that is also preserved under reducing/denaturing conditions. A direct comparison of activation properties of the mAbs confirmed that anti-T12 was optimally mitogenic in the presence of macrophages but not PMA, while, conversely, anti-2H1 was optimally mitogenic in combination with PMA but not macrophages, suggesting that the differences in epitope specificity may account for the distinct activation properties of each mAb. Taken together, the structural and functional data strongly suggest that the CD6 membrane glycoprotein may function as a physiologically important receptor structure on human T lymphocytes.

Antibodies, Monoclonal↗

PubMed1989

Quantitation and cloning of human urushiol specific peripheral blood T-cells: isolation of urushiol triggered suppressor T-cells.

A limiting dilution assay was developed to quantitate urushiol (the antigen of poison ivy; Toxicodendron radicans) specific T cells from peripheral blood of a patient with a history of rhus (poison ivy) dermatitis. It was found that maximal sensitivity with minimal nonspecific proliferation could be produced with the use of 5 U/ml of recombinant IL2 added to the assay on day 6. This donor was found to have a frequency of urushiol specific peripheral blood T cells of (1/2935). Five interleukin 2 (IL2) dependent urushiol specific T-cell clones were generated from the peripheral blood of this patient. These T-cell clones had a CD8+ (T8+) phenotype and proliferated specifically to both extracts of Toxicodendron radicans (poison ivy) leaves and pure urushiol. Pentadecylcatechol was an inferior antigen, only stimulating proliferation of one clone. The ability of all clones to proliferate to pure urushiol, despite their having been induced with leaf extract, suggests that urushiol, or closely related catechols, represent the only allergenic constituents of Toxicodendron radicans. Lymphokine production in response to antigen varied between (0.6-5.0) units/ml of interleukin 2 (IL2) and (1.0-120) units/ml of gamma interferon. Although none of the clones showed significant cytotoxicity against NK targets, three of five lines showed considerable cytotoxicity against concanavalin A treated (lectin approximated) targets. However, cytotoxicity for rhus conjugated autologous targets was not detected. It was found that several of these CD8+ clones could suppress IgG production in the presence of rhus antigen. The isolation of these T-cells from peripheral blood several months after rhus dermatitis suggests that these clones may have a role in down regulating delayed hypersensitivity to urushiol.

Catechols↗

PubMed1989

Molecular interactions, T-cell subsets and a role of the CD4/CD8:p56lck complex in human T-cell activation.

Several T-cell structures are capable of generating intracellular signals linked to T-cell proliferation. Crosslinking of CD2, CD4 and CD45 with Ti/CD3 to several of these antigens can augment the minimal signal induced by antigen binding to the Ti/CD3 complex. Importantly, some of these regulatory structures (CD4, CD8 and CD45) are also expressed on subsets of T cells with distinct activation requirements and functional programs (helper, suppressor, suppressor-inducer and cytotoxic function). The CD4+ CD45RA+ (2H4+) subset responds well to self-Ia, poorly to soluble antigen and possesses suppressor-inducer function. A reciprocal subset CD4+ CD45RA- (4B4+) is preferentially activated by soluble recall antigens and possesses helper function. Each of these subsets can be distinguished by virtue of the differential expression of CD45 antigens. Importantly, the anti-2H4 antibody which reacts with a specific region near the N-terminus of two CD45 isoforms can effectively block its function. Crosslinking of CD4 with the Ti/CD3 complex preferentially activated the CD4+ CD45+ RA- subset, while soluble antibodies to CD2 preferentially affected the CD45 CD45RA+ subset. Thus, CD3 and CD4 more effectively synergize in the activation process on the CD4+ CD45RA- subset, a result consistent with the ability of this subpopulation to respond to recall antigens. The regulatory role of the CD4, CD8 and CD45 antigens may be mediated by an interactive network of protein-tyrosine phosphorylation and dephosphorylation. We have shown the CD4 and CD8 antigens to be associated with the T cell-specific protein-tyrosine kinase (p56lck). p56lck is a member of a family of protein-tyrosine kinases with an established ability to activate and transform mammalian cells. The CD4/CD8:p56lck complex is catalytically active as shown by its ability to phosphorylate various members of the Ti/CD3 complex. By contrast, the CD45 antigens possess protein-tyrosine phosphatase activity within their intracellular domains and are postulated to function by virtue of a regulatory interaction with CD4/CD8:p56lck and its potential substrates. Thus, the differences in the response of the CD4+ CD45RA+/- subsets to various stimuli and the expansion of T-cell subsets with distinct immunoregulatory programs may be governed by a pathway of tyrosine-mediated events.

Animals↗

PubMed1988

Characterization of CD45 and CD45R monoclonal antibodies using transfected mouse cell lines that express individual human leukocyte common antigens.

Five cell lines that express one of five isoforms of the human leukocyte common Ag (CD45) were established by transfecting a murine pre-B cell line with leukocyte common Ag cDNA constructs. Using these cell lines, the specificities of CD45 and CD45R mAb were examined. Of the 43 mAb tested, 25 antibodies recognized sequences common to all five isoforms, 16 antibodies recognized isoforms that include exon A encoded sequences, one antibody recognized isoforms that include exon B encoded sequences, and one antibody recognized only the isoform that does not include either exon A, B, or C encoded sequences.

Animals↗

PubMed1988

Development of an antigen-specific CD8 suppressor effector clone in man.

A long-term cultured IL-2-dependent keyhole limpet hemocyanin (KLH)-specific CD8 (T8) suppressor clone (5B9) was generated from a healthy donor hyperimmunized with KLH. The 5B9 clonal population suppressed in vitro anti-KLH antibody response but did not suppress anti-TT antibody response or PWM-driven IgG synthesis. Moreover, 5B9 cells could not suppress anti-TT antibody response even in the presence of free KLH. 5B9 cloned cells suppressed the anti-KLH antibody response of B cells cultured with CD4+4B4+ cells without requiring the presence of CD8+ cells. This KLH-specific CD8 suppressor clone is an effector type rather than an inducer type of suppressor T cell. The cloned cells expressed alpha- and beta-TCR proteins (defined by WT-31 antibody) on their cell surface. More importantly, the CD3:TCR complex was functionally important in the suppression induced by this clone, because after CD3 antigen modulation from its cell surface, the suppressor effector function was abolished.

Adjuvants, Immunologic↗

PubMed1988

2H1--a novel antigen involved in T lymphocyte triggering.

A mAb anti-2H1, was produced against PHA-activated T cells from a lower primate, Aotus trivirgatus. Anti-2H1 reacted with 90% of peripheral T cells but was found to react with only 10% of thymocytes and some, but not all, leukemic T cell lines. 2H1 expression was dramatically increased when thymic cells were activated by Con A plus PMA. In contrast, anti-2H1 did not react with B cells, macrophages, null cells, or hematopoietic stem cell lines. More importantly, anti-2H1 antibody can induce T cell activation and proliferation in synergy with PMA or anti-T11(3). SDS-PAGE analysis of polypeptides immunoprecipitated with anti-2H1 showed two major polypeptides of 140 and 105 kDa. Thus, the 2H1 Ag can be distinguished from T3, T11, and 9.3 Ag. These results indicate that the 2H1 Ag appears to be involved in the activation of T lymphocytes.

Animals↗

PubMed1988

The 2H4 (CD45R) antigen is selectively decreased in multiple sclerosis lesions.

To analyze expression of the 2H4 (CD45R) Ag on inflammatory cells in the central nervous system immune response, immunohistochemical staining with a panel of anti-T cell mAb was performed on central nervous system tissues from 12 patients with multiple sclerosis (MS) and 8 patients with viral encephalitis. Only rare cells were stained with anti-2H4 in MS plaques, plaque edges, and adjacent white matter, whereas 2H4+ cells were more numerous in viral encephalitis (p less than 0.001). By contrast, no quantitative differences were found between MS plaque edges and viral encephalitis with anti-4B4 (helper-inducer function associated), anti-CD4, anti-CD3, and anti-IL-2R mAb, although there were fewer CD8+ cells in MS (p less than 0.01). These data indicate that the 2H4 Ag is selectively decreased and, because it is associated with suppressor-inducer function of CD4+ cells, that there may be a defect in the down-regulation of the in situ immune response in MS.

Acute Disease↗

PubMed1988

Human T cells can be directed to lyse tumor targets through the alternative activation/T11-E rosette receptor pathway.

We investigated the ability of human T cells to be directed to lyse murine and human tumor targets by antibodies (Ab) to the T11-E rosette (CD2) receptor. We found that the human cytotoxic T lymphocyte clone TBI-6, which is specific for the Epstein-Barr virus-transformed cell line, CM-EBV, could be directed to lyse the Fc receptor-positive murine tumor P388D1, by the combination of anti-T11(2) plus anti-T11(3) Ab. This activation and lysis was demonstrable only with an Fc receptor expressing tumor target and only with those Ab or with anti-T3 (CD3) Ab but not with other anti-T11 Ab or other Ab directed against surface structures on the clone. We therefore constructed heterodimeric Ab consisting of anti-T11(2) or anti-T11(3) Ab and the J5 anti-common acute lymphoblastic leukemic antigen (anti-CALLA) Ab. The purity and retained functional properties of the dimers were demonstrated by sodium dodecyl sulfate-polyacrylamide gels, fluorescence-activated cell sorter analysis on relevant cells, and by the ability of these conjugates to activate human peripheral blood lymphocytes to proliferate. These heterodimeric Ab conjugates were shown to be able to direct the lysis of CALLA+ targets by TBI-6. The specificity of this lysis was demonstrated by the inability of these heterodimers to direct the lysis of CALLA- targets by the cytotoxic T lymphocyte clone, and by the ability of excess free J5, but not an irrelevant Ab of the same isotype, to block this type of lysis. The potential clinical significance of these reagents is discussed.

Antibodies, Monoclonal↗

PubMed1988

Loss of functional suppression is linked to decreases in circulating suppressor inducer (CD4+ 2H4+) T cells in multiple sclerosis.

A consistent immunological finding in patients with progressive multiple sclerosis is a loss of functional suppression. We have recently found decreases in suppressor inducer T cells in progressive multiple sclerosis as measured by two-color immunofluorescence using differentiation markers CD4 and 2H4. In the present study, we examined the relationship between functional suppression and circulating CD4+ 2H4+ T cells using a two-stage assay. (1) T cells were stimulated for 7 days with irradiated non-T cells (autologous mixed lymphocyte reaction [AMLR]) and harvested. It has previously been shown that suppressor T cells are generated during the course of the AMLR. (2) The AMLR-generated suppressor T cells were then incubated with mononuclear cells plus pokeweed mitogen, and immunoglobulin (Ig) synthesis was measured. There was less AMLR-induced suppression of IgG synthesis in patients with progressive multiple sclerosis as compared with normal subjects and patients with other neurological diseases. More importantly, there were significant correlations between decreases in circulating CD4+ 2H4+ cells and the AMLR (p = 0.009). Thus, the decreases in functional suppression and the decreases in the AMLR in multiple sclerosis appear tightly linked to CD4+ 2H4+ cells, and their measurement provides a means to monitor suppressor function phenotypically. Decreases in suppressor inducer T cells may in part explain immunoregulatory abnormalities observed in multiple sclerosis.

Biological Assay↗

PubMed1988

Dual-label immunocytochemistry of the active multiple sclerosis lesion: major histocompatibility complex and activation antigens.

Fresh-frozen autopsy material containing active inflammatory lesions from 9 different patients with multiple sclerosis (MS) was analyzed by immunocytochemistry using a panel of monoclonal antibodies, and a dual-label immunocytochemical method was developed which permitted the simultaneous detection of two different surface markers on a single cell. We now report the following. (1) The predominant T-cell phenotype within MS lesions is CD2,3,8. This phenotype marks the suppressor-cytotoxic subset. (2) These cells do not express the natural killer cell marker NKH-1, which is present on a subset of CD8-positive cells in peripheral blood. (3) The infiltrating cell expresses class I (HLA A, B, C), but not class II (DR and DQ), major histocompatibility complex (MHC) molecules. (4) Other T-cell surface molecules, including the activation antigens interleukin-2 receptor, Ta1, and T11-3, as well as the marker 2H4, are largely not expressed. (5) Endothelial cells express both class I and class II MHC molecules and the 4B4 molecule in both MS and control tissue. (6) Astrocytes within the vicinity of MS lesions are predominantly class II MHC-negative. These results demonstrate that the T-cell infiltrate present in MS tissue on autopsy has a restricted phenotypic profile, but they also raise the possibility that, within this population, few activated effector cells are present.

Antigens, Surface↗

PubMed1988

Role of the 2H4 molecule in the activation of suppressor inducer function.

The monoclonal antibody anti-2H4 recognizes a 220-kDa and 200-kDa glycoprotein and subdivides T4+ cells into distinct subpopulations: the T4+2H4+ inducer of suppression and the T4+2H4- inducer of help. The T4+2H4+ subset has been shown to play a crucial role in the activation of T8+ suppressor cells. In the present study, we attempted to determine whether the 2H4 molecule itself may be involved in initial triggering of suppressor inducer function. The results show that the addition of anti-2H4 antibody to a mixture of B and T cells resulted in a marked suppression of pokeweed mitogen-driven Ig synthesis. When anti-2H4 was added to B cell cultures containing T4+2H4+ or T4+2H4- cells but lacking T8 cells, no suppression was generated. In addition to the requirement for T8 cells, no suppression was generated if T4+2H4+ cells were absent. These results suggest that the anti-2H4 antibody contributes to the activation of the T4+2H4+ lymphocyte subset, which in turn induces T8 cells to suppress B cell Ig synthesis. Biochemical analysis of the T4+2H4+ subset of lymphocytes indicated that the in vitro addition of anti-2H4 antibody resulted in an increased expression of the 220-kDa and 200-kDa structure on T4 cells. We conclude that perturbation of the 2H4 molecule may potentiate the activation of the suppressor inducer subset and that the T200 molecule may be directly involved in suppressor inducer function.

Antibodies, Monoclonal↗

PubMed1988

CD4+CD45R+ cells are preferentially activated through the CD2 pathway.

CD4 cell subsets, CD4+CD45R+ (CDw29-) cells and CD4+CD45R- (CDw29+) cells, can be differently triggered by various stimuli and possess distinct functions. In the present study, cell activation in CD4+CD45R+ and CD4+CD45R- subsets mediated by CD3-Ti antigen-receptor complex or CD2 molecule were examined by using anti-CD3 antibody or pairs of anti-CD2 antibodies (anti-T11(2) and anti-T11(3) antibodies). The results showed that CD4+CD45R+ cells were preferentially activated through the CD2 pathway, whereas both subsets were equally activated through the CD3-Ti antigen-receptor pathway when a second signal such as monocytes or interleukin 2 was present. The different responsiveness of CD4+CD45R+ and CD4+CD45R- subsets through the CD2 molecule did not appear to be due to differences in the distribution or number of T11(2) and T11(3) determinants. These data suggest that some part of the functional diversity of CD4 cell subsets might be explained by the differences in cell activation through the CD2 molecule.

Antigen-Antibody Reactions↗