Immunoregulatory T lymphocytes in man. Cell surface molecules involved in their function.
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Antigens, Differentiation, T-Lymphocyte↗
Biomedical subjects
E G Engleman
Publications and source records attributed to E G Engleman.
Defective cell-mediated immunity in leprosy: failure of T cells from lepromatous leprosy patients to respond to Mycobacterium leprae is associated with defective expression of interleukin 2 receptors and is not reconstituted by interleukin 2.
Patients with lepromatous leprosy (LL) but not borderline tuberculoid leprosy (BT) have defective cell-mediated immune responses to Mycobacterium leprae, despite normal responses to other stimuli, as judged by in vivo skin testing and in vitro lymphocyte transformation. To investigate the basis of the immune defect in LL patients, we studied the ability of patient mononuclear leukocytes to produce interleukin 1 (IL 1) and interleukin 2 (IL 2) upon stimulation with M. leprae, and determined the ability of exogenous IL 1 and IL 2 to reconstitute the LL patient response to this antigen in vitro. Equal numbers of adherent non-T cells from LL and BT patients produced similar amounts of IL 1 upon challenge with M. leprae, and addition of IL 1 to the culture medium failed to reconstitute the response of lymphocytes from LL patients to M. leprae. On the other hand, T cells of LL patients failed to express receptors for IL 2 or to produce IL 2 in response to M. leprae, whereas similarly treated T cells of BT patients both expressed IL 2 receptors and produced IL 2. Finally, recombinant human IL 2 purified to homogeneity as well as crude supernatants of mitogen-activated lymphocytes failed to reconstitute the response of LL patients to M. leprae. These results suggest that T cells of LL patients fail to respond to M. leprae despite an ability to produce IL 1 and that their failure to express receptors for IL 2 may explain both defective proliferation and the failure of exogenous IL 2 to reconstitute the response.
Animals↗
Lymphocyte subsets and surface molecules in man.
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Animals↗
Immunoregulatory T cell circuits in man. Identification of a distinct T cell subpopulation of the helper/inducer lineage that amplifies the development of alloantigen-specific suppressor T cells.
Regulation of the immune response in man is dependent on interactions between cells of helper/inducer (Leu-3+/T4+) lineage and cells of suppressor/cytotoxic (Leu-2+/T8+) lineage. By using the mixed leukocyte reaction (MLR) as a model system, we have shown previously that alloantigen-primed Leu-3+ cells induce autologous Leu-2+ cells to differentiate into suppressor T cells that specifically inhibit the response of fresh T cells to the original allogeneic stimulator cells. The current study was undertaken to analyze the roles in this suppressor circuit of subpopulations of Leu-3+ cells distinguished from one another on the basis of their binding or lack of binding to monoclonal anti-Leu-8 antibody. Although both Leu-3+,8- and Leu-3+,8+ T cells proliferated in allogeneic MLR, alloactivated Leu-3+,8+ cells alone induced proliferation and differentiation of Leu-2+ suppressor cells. Leu-3+,8+ cells also induced Leu-3+,8- cells to proliferate, and following their activation in this manner, such autoactivated Leu-3+,8- cells augmented the differentiation of Leu-2+ suppressor cells, but only in the presence of alloactivated Leu-3+,8+ cells. Furthermore, this effect, like the suppressor effect, was specific for the inducer cells, and thus indirectly for the HLA-DR antigens of the original allogeneic stimulator cells as well. These results indicate that alloantigen-primed Leu-3+,8+ cells not only activate specific Leu-2+ suppressor cells but also activate specific Leu-3+,8- suppressor-amplifier cells, and in combination, these cells exert potent feedback inhibition of MLR.
Antibodies, Monoclonal↗
Functional characterization of human T lymphocyte subsets distinguished by monoclonal anti-leu-8.
Previous studies have shown that monoclonal anti-Leu-8 antibody identifies functionally distinct subpopulations within both the Leu-2 (T8+) and Leu-3 (T4+) lineages of human T lymphocytes. We now report in detail on the tissue distribution of the Leu-8 antigen and on extensive functional studies of T cells subsets distinguished by their expression or lack of expression of this marker. Leu-8 is present on a wide variety of hematologic cells, including granulocytes, T and B lymphocytes, monocytes, and null or NK cells. Within lymph nodes and tonsils, Leu-8 is absent from both B and T cells within germinal centers but is present on nearly all paracortical lymphocytes. Leu-8 is present on most but not all EBV-transformed B cell lines, reflecting its presence on a subset of normal peripheral blood B cells. None of six malignant T cell lines tested were Leu-8+, whereas most circulating T cells are Leu-8+. Although standard immunoprecipitation techniques failed to demonstrate any specific bands on SDS polyacrylamide gels, the antigenic determinant recognized by anti-Leu-8 is protein or protein-associated, because brief treatment of target cells with pronase abrogated binding of anti-Leu-8. Both Leu-3+8+ and Leu-3+8- cells proliferated in response to several soluble antigens and to autologous and allogeneic non-T cells. Nonetheless, nearly all of the helper T cells for PWM- and AMLR-induced PFC were contained within the Leu3+8- subset. Optimal suppression of the PWM-induced PFC response required both Leu-2+8+ and Leu-2+8- cells, and irradiation of either subset with 3000 R abrogated the capacity of the recombined subsets to effect suppression. In contrast to help for B cell differentiation, both Leu-3+8+ and Leu-3+8- cells were capable of amplifying the development of allospecific T killer cells; precursor and effector T killer cells could be found within both Leu-2+8+ and Leu-2+8- subpopulations. The correlation between Leu-8 phenotype and selected immune functions of T cells (and B cells; see companion paper) indicates that anti-Leu-8 distinguishes important immunoregulatory T and B lymphocyte subsets in man.
Animals↗
Antigen-specific suppressor T lymphocytes in man make use of the same set of surface molecules as do cytolytic T lymphocytes: roles of Leu-2/T8, Leu-4/T3, Leu-5/T11, LFA-1 molecules.
When cultured with autologous antigen-primed Leu-3+ lymphoblasts, Leu-2+ cells differentiate into suppressor T cells (Ts) that specifically inhibit the responses of fresh autologous Leu-3+ cells to the priming antigen. We have shown previously that the Leu-4/T3 (CD-3) molecular complex and HLA-A,B molecules on the surface of Leu-3+ inducer blasts are recognized by Leu-2+ Ts during their differentiation. This study examines the role of various cell surface molecules expressed by Leu-2+ Ts during the inductive and effector phases of suppression. Leu-2+ cells were treated in the absence of complement with a variety of monoclonal antibodies recognizing distinct human lymphoid antigens either before or after their activation with alloantigen-primed Leu-3+ blasts. Antibodies to Leu-2/T8 (CD-8) and lymphocyte function-associated antigen-1 (LFA-1) (CDw-18) molecules inhibited not only the generation but also the effector function of Leu-2+ Ts. Although antibodies to Leu-4/T3 (CD-3) and Leu-5/T11 (CD-2) molecules caused profound inhibition of the activation of Ts, these antibodies failed to inhibit the effector function of Ts. On the contrary, anti-Leu-4 antibody consistently augmented the suppressor effect of Ts. Antibodies directed against Leu-1/T1 (CD-5), Leu-3/T4 (CD-4), LFA-3, and class I (HLA-A,B,C) and class II (HLA-DR,DQ) major histocompatibility complex molecules had no effect on either the generation or the effector function of Ts. These results suggest the involvement of Leu-2/T8 (CD-8), Leu-4/T3 (CD-3), Leu-5/T11 (CD-2), and LFA-1 (CDw-18) molecules on the surfaces of Leu-2+ cells in the activation and effector functions of Ts.
Antibodies, Monoclonal↗
Recombinant interleukin 2 enhanced natural killer cell-mediated cytotoxicity in human lymphocyte subpopulations expressing the Leu 7 and Leu 11 antigens.
Highly purified recombinant human interleukin 2 (rIL 2) markedly augments the natural killer (NK) cell-mediated cytotoxicity of peripheral blood lymphocytes. In this study, we examined the cellular and metabolic basis of rIL 2-mediated activation of human lymphocyte subpopulations expressing the NK cell-associated surface antigens Leu 7 and Leu 11. All rIL 2-responsive cytotoxic NK cells were found within the subset of lymphocytes expressing the Leu 11 marker, an antigen associated with the Fc-IgG receptor on human NK cells. Cells lacking the Leu 11 antigen, including cells expressing another NK cell-associated marker, Leu 7, did not express NK cell-mediated cytotoxicity either before or after rIL 2 treatment. By contrast, rIL 2 augmented the NK activity of both Leu7-,11+ and Leu 7+,11+ subpopulations. Activation of Leu 11+ NK cells resulted from a direct effect of rIL 2 on these cells and neither required nor was amplified by the presence of T lymphocytes. Enhanced NK cell-mediated cytotoxicity occurred within 4 hr after exposure to rIL 2, and was blocked by the protein synthesis inhibitor cyclohexamide, but not by the DNA synthesis inhibitor mitomycin C or 1500 rad of x-irradiation. Neither Tac antigen, a high-affinity receptor for IL 2, nor other activation markers, such as transferrin receptor or HLA-DR antigen, were detectable on a significant proportion of Leu 11+ cells, either before or after incubation with rIL 2 for 48 hr. In addition, saturating concentrations of antibodies to each of these markers had no effect on the enhancement of NK activity by rIL 2. Finally, preliminary experiments with neutralizing antibodies to gamma- and alpha-interferons also failed to prevent rIL 2 enhancement of NK cell-mediated cytotoxicity, suggesting that rIL 2 does not mediate its effect via release of these cytokines.
Antibodies, Monoclonal↗
Human bone marrow and peripheral blood T lymphocyte depletion: efficacy and effects of both T cells and monocytes on growth of hematopoietic progenitors.
The efficacy of four separate methods of human bone marrow T lymphocyte depletion was assessed, and the effect of T cells and monocytes on in vitro growth of marrow (CFU-GEMM, BFU-E, and CFU-GM) and peripheral blood (BFU-E) hematopoietic progenitors was determined. Extent of T cell depletion was assessed by multiparameter fluorescent cell sorter (FACS) analysis and by functional studies. Cells staining positively by FACS analysis for one or more of three separate fluorescent pan-T cell monoclonal antibodies (MCAbs) comprised 8.4% to 9.5% of control marrow mononuclear cells (MNCs). T cells constituted 3.2% to 5.1% of marrow following single, sequential, or combination treatment with two different pan-T cell MCAbs (Leu 1 and TM1) plus complement, 1.5% to 2.2% of marrow following solid-phase immunoabsorption ("panning"), 0.2% of marrow after sheep cell rosetting, and only 0.05% of marrow after FACS selective cell sorting and gated separation. T cells made up 59% to 73% of control peripheral blood MNCs and 0.8% to 2.8% of peripheral MNCs following sheep cell rosetting plus treatment with Leu 1 MCAb and complement. Mitogen (PHA, Con A) and allogeneic MLC-induced blastogenic responses (stimulation indices, experimental/control or E/C) revealed a concordant decrement in marrow T cell function after MCAb plus complement (E/C of 3.9 to 9.0), after panning (E/C of 1.6 to 3.5) and after sheep cell rosetting (E/C of 0.7 to 1.3), compared with control marrow (E/C of 5.3 to 15.7). After T cell depletion, marrow BFU-E growth was 95% to 120% of control, CFU-GM growth was 90% to 108% of control, and CFU-GEMM growth was 89% to 111% of control. Marrow T cell and/or monocyte depletion did not alter erythropoietin-dependent BFU-E growth in the absence of Mo-conditioned medium (81% to 95% of control), and the addition of as many as 50 to 100 X 10(3) purified marrow monocytes or T cells to 10(5) autologous nonadherent T cell-depleted marrow target cells had a negligible (P greater than .1) effect on marrow BFU-E growth in vitro. Peripheral blood (PB) BFU-E/10(5) T-depleted target cells were 106% +/- 19% of expected; PB BFU-E growth was significantly diminished after monocyte depletion alone (7% +/- 6% of expected) or after monocyte plus T cell depletion (8% +/- 4% of expected).(ABSTRACT TRUNCATED AT 400 WORDS)
Antibodies, Monoclonal↗
Progress toward understanding self-tolerance.
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Animals↗
Maturational and functional diversity of human B lymphocytes delineated with anti-Leu-8.
Human B lymphocyte subpopulations distinguished by their expression of the Leu-8 antigen were studied and found to differ in their respective maturational state and functional repertoire. The absence of Leu-8 expression correlated with an early step in antigen-driven B cell differentiation in that 1) as presented in the companion paper, germinal center B lymphocytes were uniformly Leu-8-, whereas mantle zone B cells were virtually all Leu-8+; 2) treatment of Leu-8+ B cells with the combination of rabbit anti-human mu-chain and B cell growth factor (BCGF), but not with either reagent alone, caused the loss of Leu-8 expression in addition to causing these cells to proliferate; and 3) only the Leu-8- B cell subset contained cells expressing the 4F2 activation antigen. Functional studies of peripheral blood B cells revealed that B cells giving rise to antibody-forming cells in the presence of T cells and pokeweed mitogen (PWM) were found almost exclusively in the Leu-8- subset of B cells, even though this subset comprised a minority of circulating B lymphocytes. By contrast, Leu-8+ B cells proliferated more vigorously than Leu-8- B cells to formalinized Staphylococcus aureus Cowan I (SAC). These data demonstrate that Leu-8 is an important maturational and functional marker for human B lymphocytes.
Antibodies, Monoclonal↗
Rescue of human monoclonal antibody production from an EBV-transformed B cell line by fusion to a human-mouse hybridoma.
A human-mouse cell line that is hypoxanthine-aminopterin-thymidine sensitive and ouabain resistant was derived from a fusion between human B lymphocytes and a mouse myeloma line. This new mutant, when fused to a relatively unstable EBV-transformed B cell secreting a human monoclonal anti-A (red blood cell antigen) antibody, resulted in stable hybridomas capable of long term production of the specific human monoclonal antibody. Furthermore, some of the hybrid clones secreted antibody in far greater titer than the original EBV cell line. We conclude that fusion to this human-mouse line is an efficient approach to the production of human monoclonal alloantibodies and an effective method of 'rescuing' secretion of desired antibody from EBV cell lines.
ABO Blood-Group System↗
Human recombinant interleukin-2 partly reconstitutes deficient in-vitro immune responses of lymphocytes from patients with AIDS.
The lymphokine interleukin-2 is required for the development of various cell-mediated immune functions that are known to be deficient in patients with acquired immunodeficiency syndrome (AIDS). The effects of pure human recombinant interleukin-2 (rIL-2), produced by Escherichia coli containing the cloned human gene, on in-vitro immune responses were studied in 16 patients with AIDS and 10 age-matched healthy heterosexual men. Exposure of lymphocytes from most AIDS patients to 1-100 U/ml rIL-2, increased mitogen and alloantigen induced proliferation and augmented natural killer (NK) cell function in a dose-dependent manner. NK activity was the function most consistently improved, with deficient patient responses uniformly restored to normal after incubation of effector cells with rIL-2. Patient responsiveness to rIL-2 did not appear to depend upon the primary manifestation of disease (opportunistic infection, Kaposi's sarcoma, or both) or other clinical variables. rIL-2 also augmented the responses of lymphocytes from health subjects, but to a lesser degree. Pure rIL-2 seems capable of at least partly reconstituting some in-vitro immunological defects characteristic of AIDS. The availability of highly purified rIL-2 makes in-vivo testing feasible.
Acquired Immunodeficiency Syndrome↗
Immunoregulatory T cell circuits in man--an overview of recent advances.
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Antibodies, Monoclonal↗
Functional and quantitative alterations in T lymphocyte subpopulations in acute toxoplasmosis.
The cellular immune response to Toxoplasma gondii has been studied in 23 patients with acute toxoplasma infection. Abnormalities of T cell subpopulations included a marked and significant elevation in suppressor (Leu 2) T cells in patients with prolonged symptoms due to acute infection and either a decrease in the number of T helper cells or an increase in the number of suppressor cells--or both--in patients with asymptomatic lymphadenopathy. There was no significant difference in lymphocyte proliferation to phytohemagglutinin or pokeweed mitogen among the various groups tested. The peak lymphocyte response to toxoplasma antigen, however, was significantly depressed in patients with acute infection compared with that in chronically infected control patients. The kinetics of the depression were consistent with the induction of a non-Leu 2 suppressor cell. These results demonstrate marked quantitative alterations in T lymphocyte subpopulations and functional alterations of T cells to toxoplasma antigen during infection with T. gondii.
Antigens, Protozoan↗
Soluble antigen-primed inducer T cells activate antigen-specific suppressor T cells in the absence of antigen-pulsed accessory cells: phenotypic definition of suppressor-inducer and suppressor-effector cells.
This study was undertaken to characterize interactions among human T cell subpopulations involved in the generation of suppressor T cells specific for a soluble antigen. Purified PPD-primed Leu-3+ cells, when co-cultured for 7 days with fresh autologous Leu-2+ cells, induced differentiation of Leu-2+ but not Leu-3+ cells into specific suppressor T cells, which subsequently inhibited the proliferative response of fresh Leu-3+ cells to PPD but not to tetanus toxoid or allogeneic non-T cells. The PPD-specific suppressor effect of activated Leu-2+ cells was not due to altered kinetics of the PPD response and also extended to the secondary response of PPD-primed Leu-3+ cells. Furthermore, only those Leu-2+ cells that lacked the 9.3 marker, an antigen present on the majority of T cells including the precursors of cytotoxic T cells, differentiated into suppressor T cells. To analyze the inducer population, fresh Leu-3+ cells were separated into Leu-3+,8- and Leu-3+,8+ subpopulations with anti-Leu-8 monoclonal antibody, activated with PPD, and then were examined for inducer function. Although both Leu-3+,8- and Leu-3+,8+ cells proliferated in response to PPD and upon activation expressed comparable amounts of HLA-DR (Ia) antigens, the Leu-3+,8+ subpopulation alone induced Leu-2+ cells to become suppressor-effectors in the absence of PPD-pulsed autologous non-T cells. Once activated, however, Leu-2+ suppressor cells inhibited the PPD response of both Leu-3+,8- and Leu-3+,8+ cells. These results indicate that antigen-primed Leu-3+,8+ inducer cells can directly activate Leu-2+, 9.3- precursors of antigen-specific suppressor T cells in the absence of antigen-pulsed autologous non-T cells.
Antigens, Bacterial↗
A human alloreactive inducer T cell clone that selectively activates antigen-specific suppressor T cells.
We showed previously that T cells with the phenotype Leu-3+,8+ are required for the induction of antigen-specific Leu-2+ suppressor cells. Furthermore, when mixed lymphocyte reactions are carried out in the presence of 1 microgram/ml cyclosporin A (CsA), such cultures lead preferentially to the activation of alloantigen-specific suppressor-inducer Leu-3+,8+ cells. In an attempt to generate a clone of T cells with such specific suppressor-inducer properties, we activated Leu-3+,8+ T cells with allogeneic (HLA-DR4+) lymphocytes in the presence of CsA. Clone SP-21, derived by propagating such activated T cells with conditioned medium containing IL 2, is a noncytotoxic, nonsuppressor clone that specifically proliferates to allogeneic cells bearing HLA-DR4 antigen. When cultured with fresh autologous Leu-2+ cells in the absence of HLA-DR4+ cells, clone SP-21 selectively activates Leu-2+ suppressor cells, which inhibit the response of fresh Leu-3+ cells to DR4+ stimulator cells. On the other hand, clone SP-21 fails to induce cytolytic T cells or to help B cell differentiation. These results demonstrate that a T cell clone with a remarkably narrow functional repertoire nonetheless contains and transmits all of the signals necessary for the activation of antigen-specific suppressor cells.
B-Lymphocytes↗
Activation of antigen-specific suppressor T lymphocytes in man involves dual recognition of self class I MHC molecules and Leu-4/T3-associated structures on the surface of inducer T lymphocytes.
We showed previously that fresh Leu-2+ T cells respond to autologous antigen-primed Leu-3+ T cells by proliferation and differentiation into suppressor T cells (Ts) that specifically inhibit the response of fresh Leu-3+ cells to the original priming antigen. This study was undertaken to characterize the role of various cell surface molecules expressed by antigen-primed Leu-3+ cells in their activation of Leu-2+ Ts cells. Alloactivated Leu-3+ blasts were treated in the absence of complement with a variety of monoclonal antibodies recognizing distinct antigens on human lymphoid cells, and then were examined for their functional effects on fresh autologous T cells. Prior treatment of Leu-3+ blasts with anti-Leu-4 or anti-HLA-A,B,C framework antibodies, but not with anti-Leu-1, anti-Leu-3, anti-Leu-5, or anti-HLA-DR framework-specific antibodies, not only blocked proliferation of fresh Leu-2+ cells, it also prevented their differentiation into Ts cells. Furthermore, after their activation by Leu-3+ blasts, Leu-2+ Ts cells inhibited the response of fresh Leu-3+ cells from only those individuals who shared HLA-A,B phenotypes with suppressor-effector cells. These results suggest that both the inductive and effector phases of suppression involve dual recognition of autologous class I MHC molecules and structures associated with the Leu-4 (T3) molecule on the surface of antigen-reactive Leu-3+ cells.
Antibodies, Monoclonal↗
Reduced in vitro immune responses of purified human Leu-3 (helper/induced phenotype) cells after total lymphoid irradiation.
Patients treated with total lymphoid irradiation (TLI) for intractable rheumatoid arthritis showed marked decreases in the in vitro proliferative responses of peripheral blood mononuclear cells (PBM) to antigens and mitogens. To determine whether an intrinsic deficit in helper/inducer cell proliferation contributed to decreased responses, cells of the helper/inducer phenotype were purified from the PBM of treated patients by using monoclonal anti-Leu-3 antibody and a modified panning procedure. The purified Leu-3 cells obtained after TLI showed a marked reduction in [3H]thymidine incorporation in response to allogeneic lymphocytes, PHA, Con A, and several protein antigens, as compared with that of cells from the same patients obtained before TLI. In addition, the quantity of Leu-3 surface antigen on the panned cells was reduced after TLI. The results suggest that TLI induces prolonged qualitative as well as quantitative changes in circulating Leu-3 T cells. These changes may contribute to the clinical effects of TLI.
Antigens, Surface↗