[Possible role of the T-cells in regulating in situ hematopoiesis]

The aim of the study was to reveal the possible role of T cells in the negative regulation of hematopoiesis. The main experimental approach included incubation of bone marrow cells obtained from mice of different strains with the anti-serum against a specific marker of suppressor T cells--antigen I-J. Anti-I-Jk serum-treated cells and cells treated with nontoxic normal mouse serum or non-treated cells (controls) were further incubated with complement and tested for their CFUs content, using Till & McCulloch exocolonization technique. Treatment with anti-I-Jk serum had a stimulating effect on the CFUs colony formation in mice of the appropriate haplotype (CBA, AKR, A/Sn) bearing I-Jk, but not I-Jb (CC57Br) allele. The same results were obtained in transfer experiments using spleen cells; only in this case stimulating effect was observed in 7-8-day CFUs, while with the marrow transplant augmentation it was seen both 7-8 and 11-12 days following grafting. The seeding efficiency of CFUs was not changed after incubation with anti-I-J serum. The data prove that indigenous for the spleen and bone marrow of mice cells expressing I-J determinants are involved in the negative regulation of hematopoiesis in situ.