We have investigated the effects of heat shock on T-cell induction and selection in vitro. We find that when cell preparations containing T lymphocytes are incubated for 30 min at 42TC, a selective proliferation of y68 T cells bearing the y8 T-cell antigen receptor follows. A greater enrichment of Y6+ T cells is observed, upon preexposure to mycobacterial antigens in vivo. By comparing the effects of heat shock with that of mitogen or specific T-cell triggering by conventional antigens and by analyzing the v6 T-cell receptor genes expressed in cells that proliferate as a result of heat shock induction, we conclude that a subset of murine y8 T cells react to antigens on self cells in which a heat shock response was induced. GBq) was added to the medium and the cells were cultured in a 5% C02/95% air incubator for a further 6 hr.Cell Cultures. Lymphocyte suspensions from lymph nodes were prepared by standard procedures, and RPL populations were prepared as described (10). Cells were cultured in Iscove's modified Dulbecco's medium supplemented with 10% fetal calf serum essentially as described (10, 11). Where applicable, lymphokines added after 3 days in culture were recombinant interleukin 1 and recombinant interleukin 2 (10 units/ml and 40 units/ml, respectively; gifts of P. Lomedico, Roche, Nutley, NJ). In general, 5 days after the addition of lymphokines, viable cells were analyzed. Where indicated,
The differential effects of H-2 IAk-specific T helper cells, their soluble factors and Sepharose-coupled anti-mu antibodies on the growth and differentiation of pre-activated B cells were studied. It was found that the prolonged growth of pre-activated B cells required activation signals from major histocompatibility complex (MHC)-restricted T helper cells or Sepharose-coupled anti-mu antibodies. The MHC-restricted T helper cells induced both prolonged growth and differentiation of activated B cells. Anti-mu antibodies together with T helper cell-derived soluble factors induced prolonged growth of activated B cells, but no differentiation into Ig secretion was detected. The inhibition of Ig secretion in anti-mu cultures could be overcome to some extent by either MHC-restricted T helper cells or lipopolysaccharide together with soluble factors. It was also observed that T helper cell interactions were needed for long-term in vitro culture of pre-activated B lymphocytes.
Heterogeneity in antigen recognition of an alloreactive helper T-cell line was studied by repeated limiting dilution cloning. Analysis of the fine specificities of these clones showed that the gain of reactivity to new antigens by the T-cell line included the generation of non-cross-reactive T cells specific to new major histocompatibility (MHC) antigens. Analysis of function revealed that all the T-cell clones studied had similar cell surface antigens and secreted interleukin 4 (IL-4) and IL-5/IL-3 but not IL-2 or gamma interferon (IFN-gamma). The T-cell clones served as helper cells for B cells expressing the appropriate MHC antigens to both clonal proliferation and differentiation into antibody-producing cells.
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