Maturational requirements of murine differentiation antigens 1 and 2 that are operative in isogeneic lymphocyte interactions

Maturation of two murine differentation antigens (MDA's) on B cells responsible for stimulating blastogenesis in types 1 and 2 isogeneic lymphocyte cultures (ILCs) was studied. Bone marrow (BM) cells, known to lack both MDA's were used to reconstitute X-irradiated CBA/J mice and splenic cells were removed from these mice at intervals to determine when they became capable of stimulating neonatal T cells (type 1 ILC) and adult lymph node cells (type 2 ILC). It was found that MDA-2 matures on BM cells in a splenic environment apparently devoid of thymic influence, whereas MDA-1, known to exist on lymph nodal as well as splenic B cells, requires for its complete expression assistance from mature T cells. Both MDA's were prohibited from functioning in a stimulating way by addition of 1a specific antibodies to type 1 ILC, suggesting close association, if not identity, of MDA's with 1a antigens