Abstract
The human autologous mixed lymphocyte reaction, peripheral blood T cells are stimulated to proliferate when co-cultured with irradiated, autologous, non-T cells was studied. ($\sp3$H) -thymidine uptake was maximal on day 7 and observable on day 9. Non-adherent and adherent fractions of non-T population and lectin-activated T cell blasts contributed. Unseparated non-T stimulator cells were used.Autologous T cells, when added as irradiated third party cells, reduced AMLR proliferative responses. Depletion of Fc IgG receptor-bearing cells (T$\gamma$) from T cell population by (a) IgG-sensitized ox erythrocyte rosetting (EA-rosettes) or (b) adsorption of the T$\gamma$ cells onto a Sepharose 6MB $\sim$ BSA/anti-BSA immune complex column resulted in enhanced AMLR proliferation not attributed solely to an increase in CD8+ AMLR responder cell phenotype. Isolated T$\gamma$ populations exhibited a reversed helper/suppressor phenotype containing HLA DR+ and CD8+ cells. Dual labelling studies demonstrated 7-24% of CD8+ cells expressed DR antigens. After separation, AMLR proliferative capacity was localized in T-depleted population.Addition of EA-rosette isolated, T$\gamma$ cells to AMLR cultures resulted in reductions (63-87%) in ($\sp3$H) -thymidine uptake. T$\gamma$ cell-mediated suppression was radiation resistant and dose dependent, 2 $\times$ 10$\sp4$ irradiated T$\gamma$ cells suppressed proliferation of 1 $\times$ 10$\sp5$ responder (T$\gamma$-depleted) cells with maximum suppression occurring with additions of 5-10 $\times$ 10$\sp4$ T$\gamma$ cells. Using biotin-avidin affinity column chromatography, cells were depleted from T$\gamma$ population expressing certain membrane antigens. OKT8 antigen or HLA DR antigens were deleted from T$\gamma$ population, inhibitory activity was reduced.Supernatant fluids from cultures were examined from AMLR inhibitory activity. Neither allogeneic nor autologous combinations of supernatant plus AMLR culture resulted in reduced proliferation after 7 days. Supernatant fluid collected from 2-4 day AMLR cultures were tested for inhibitory activity. Elevated ($\sp3$H) -thymidine uptake was observed when supernatants were added to AMLR cultures, 2-4 day AMLR supernatants enhanced 7 day AMLR-induced ($\sp3$H) -thymidine uptake by 80%, 324%, and 166%, respectively. Supernatants from T$\gamma$ cell-containing AMLR cultures were less in enhancing 7 day AMLR-induced ($\sp3$H) -thymidine uptake--being 7%, 140%, and 42% for day 2-4 supernatants, respectively. No difference was observed in the stimulatory capacity of AMLR or AMLR + T$\gamma$x supernatants when assayed on IL-2 dependent cell line, CTLL. These supernatants were not inhibitory to IL-2 driven proliferation. (Abstract shortened with permission of author.)