Influence of major histocompatibility complex H-2LD class I molecules on spleen colony-forming units.

To test whether the major histocompatibility complex class I genes are involved in the regulation of hemopoiesis, the stem cell activities of BALB/c-H-2dm2 (Dm2) mice, which are defective in the expression of H-2L antigens, have been compared with those of the wild-type, BALB/c-Kh, in in vivo and in vitro stem cell assays. In spleen colony-forming unit assays, Dm2 as hosts consistently supported a smaller number of colonies than did BALB/c-Kh. However, both Dm2 and BALB/c-Kh supported a comparable number of colonies in in vitro granulocyte-macrophage colony-forming unit and erythroid colony-forming unit assays. These observations together suggest that the mutation in Dm2 has not affected the hemopoietic potential of the stem cells but may probably affect the hemopoietic microenvironment for the development of the stem cells.