REGULATORY EFFECTS IN-VITRO BY THYMIC MEDULLARY EPITHELIAL-CELLS ON TCR TRANSGENIC T-CELLS SPECIFIC FOR MALE H-Y ANTIGENS

To evaluate the ability of thymic epithelial cells (TEC) to influence growth and differentiation of antigen specific T cells, we have used f emale transgenic (TG) mice expressing a receptor on the majority of th eir T cells for the male (H-Y) antigen in the context of H-2D(b) antig ens. Male or female TEC expanded in serum-free medium were co-cultured with female TG thymocytes. FAC-Scan analysis after 3 days of co-cultu re did not indicate any selective deletion of subpopulations induced b y male TEC. In contrast, the presence of TEC in TG thymocyte cultures led to increased proliferation, irrespective of the type of TEC and st imulus used. Limiting dilution (LD) proliferation analyses, using irra diated male spleen cells as stimulator cells, showed increased clonabi lity of CD4-CD8+ cells, but reduced clonability of CD4-CD8+ thymocytes , in the presence of both male and female TEC. Clones from the LD cult ures were expanded for several weeks. Expanded clones all expressed th e vbeta8.2+ TG TCR. One-half of the expanded TG CD8+ T cell clones obt ained from LD cultures exhibited H-Y specific proliferation, and the m ajority of clones showed antigen-specific IL-3 secretion. Expanded clo nes did not develop into a cytotoxic machinery in the present culture system.