Biomedical subjects

G S Kansas

Publications and source records attributed to G S Kansas.

61 records · Page 4Linked to original sources

PubMed1985

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↗

PubMed1985

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↗

PubMed1984

Suppression of pokeweed mitogen-stimulated immunoglobulin production in patients with rheumatoid arthritis after treatment with total lymphoid irradiation.

Patients with intractable rheumatoid arthritis (RA) were treated with total lymphoid irradiation (TLI, 2000 rad). We previously reported long-lasting clinical improvement in this group associated with a persistent decrease in circulating Leu-3 (helper subset) T cells and marked impairment of in vitro lymphocyte function. In the present experiments, we studied the mechanisms underlying the decrease in pokeweed mitogen stimulated immunoglobulin (Ig) secretion observed after TLI. Peripheral blood mononuclear cells (PBL) from TLI-treated patients produced 10-fold less Ig (both IgM and IgG) in response to pokeweed mitogen than before radiotherapy. This decrease in Ig production was associated with the presence of suppressor cells in co-culture studies. By using responder cells obtained from normal individuals (allogeneic system), PBL from eight of 12 patients after TLI suppressed Ig synthesis by more than 50%. In contrast, PBL from the same patients before TLI failed to suppress Ig synthesis. Suppression by post-TLI PBL was also demonstrated in an autologous system by using responder cells cryopreserved before TLI. Again, only cells obtained after TLI were suppressive in four of seven patients. PBL with suppressive activity contained suppressor T cells, and the latter cells bore the Leu-2 surface antigen. In 50% of the patients studied, suppressor cells were also found in the non-T fraction and were adherent to plastic. Interestingly, the Leu-2+ cells from TLI-treated patients were no more potent on a cell per cell basis than purified Leu-2+ cells obtained before TLI. Additional experiments suggested that the suppression mediated by T cells after TLI is related to the increased ratio of Leu-2 to Leu-3 cells observed after radiotherapy.

Animals↗

PubMed1983

Changes in T-cell subsets in patients with rheumatoid arthritis treated with total lymphoid irradiation.

Patients with intractable rheumatoid arthritis (RA) were treated with total lymphoid irradiation (TLI, 2000 rads). We previously reported long-lasting clinical improvement associated with marked suppression of in vitro lymphocyte function in this group. In an attempt to better understand the mechanism of immunosuppression and clinical changes observed after TLI, we studied in greater detail changes in peripheral blood T-cell subsets identified by monoclonal antibodies. Before TLI, RA patients had a higher percentage of Leu-3 (helper subset) cells and a lower percentage of Leu-2 (suppressor/cytotoxic subset) cells than normals. Immediately after TLI, the absolute numbers of both Leu-2 and Leu-3 cells were reduced by at least 90%. Within 6-12 weeks, the number of Leu-2 cells returned to the pretreatment levels, but the levels of Leu-3 cells remained depressed for months thereafter. The lack of repopulation of Leu-3 cells resulted in a marked increase in the ratio of Leu-2 to Leu-3 cells as compared to pretreatment values (1.73 +/- 0.23 vs 0.39 +/- 0.06), and in a decrease in the percentage and absolute number of total T (Leu-1 and Leu-4) cells. The failure of Leu-3 cells (which mediate predominantly helper/inducer functions) to repopulate the peripheral blood may contribute to the prolonged clinical immunosuppression observed after TLI. Similar changes in T-cell subsets were not observed in RA patients given remittive drugs or low doses (200 rads) of radiotherapy. Thus, TLI differs from other treatment modalities with regard to its prolonged selective effect on the Leu-3 subset.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1982

Immunoglobulin secretion in the human autologous mixed leukocyte reaction. Definition of a suppressor-amplifier circuit using monoclonal antibodies.

The induction of immunoglobulin (Ig) synthesis in the autologous MLR has an absolute requirement for helper/inducer (Leu-3) T cells, whereas an excess of suppressor/cytotoxic (leu-2) cells suppresses the response. The current study was an effort to assess the immunoregulatory potential to T cells activated in the autologous mixed-leukocyte response (MLR). T cells were cultured with autologous non-T cells for 8-9 d, after which the activated T cells were fractionated into subsets with monoclonal antibodies to T cell markers and HLA-DR antigen. Each population was co-cultured in fresh autologous MLR, and on the 8th day of culture, Ig-secreting cells were measured in a reverse hemolytic plaque assay. The results show that activated Leu-2, DR+ T cells, but neither Leu-2, DR- nor Leu-3 T cells, were at least 50 times more potent as suppressors of IgM and IgG synthesis than fresh Leu-2 cells alone. The activation of this Leu-2, DR+ subpopulation required Leu-3 cells in the primary culture. Furthermore, in the absence of Leu-2 cells in the second culture, little or no suppression was observed, suggesting that the Leu-2, DR+ cells act to amplify or induce suppressor effects of fresh Leu-2 cells. This indicates that at least two distinct subpopulations of Leu-2 cells are required for maximal suppression of an immune response, and that immunoregulatory circuits analogous to those described in the mouse exist in man.

Antibodies, Monoclonal↗

PubMed1982

Dissection of immunoregulatory subpopulations of T lymphocytes within the helper and suppressor sublineages in man.

The helper/inducer (Leu-3) and suppressor/cytotoxic (Leu-2) sublineages of human peripheral blood T cells can both the subdivided into functionally distinct subsets with anti-Leu-8, a new monoclonal antibody that identifies 75 +/- 10% of the Leu-3 cells and 60 +/- 10% of the Leu-2 cells. Using the autologous MLR as a T cell-dependent stimulus for immunoglobulin synthesis, we have shown that the major helper effect for antibody formation lies within the numerically minor Leu-3,8- subset. In addition, neither Leu-2,8- cells alone suppress Leu-3-induced immunoglobulin synthesis, but in combination these subsets are markedly inhibitory. These results indicate that at least two phenotypically distinct cell types of suppressor lineage interact to produce suppression of an immune response in man.

Animals↗

PubMed1981

Treatment of intractable rheumatoid arthritis with total lymphoid irradiation.

Eleven patients with intractable rheumatoid arthritis were treated with total lymphoid irradiation (total dose, 2000 rad) in an uncontrolled feasibility study, as an alternative to long-term therapy with cytotoxic drugs such as cyclophosphamide and azathioprine. During a follow-up period of five to 18 months after total lymphoid irradiation, there was a profound and sustained suppression of the absolute lymphocyte count and in vitro lymphocyte function, as well as an increase in the ratio of Leu-2 (suppressor/cytotoxic) to Leu-3 (helper) T cells in the blood. Persistent circulating suppressor cells of the mixed leukocyte response and of pokeweek mitogen-induced immunoglobulin secretion developed in most patients. In nine of the 11 patients, these changes in immune status were associated with relief of joint tenderness and swelling and with improvement in function scores. Maximum improvement occurred approximately six months after irradiation and continued for the remainder of the observation period. Few severe or chronic side effects were associated with the radiotherapy.

Antibodies, Monoclonal↗