Characterization of a cellular inhibitory activity affecting the human autologous mixed lymphocyte reaction

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Microbiology and Immunology

First Committee Member

Laphalle Fuller, Committee Chair


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.)


Health Sciences, Immunology

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