EXPRESSION OF MEMBRANE-BOUND BURST-PROMOTING ACTIVITY IS MEDIATED BY ALLOGENEIC EFFECTOR-CELLS

To investigate whether ''self'' and ''non-self'' recognition processes are involved in murine erythropoiesis, the expression of membrane-bou nd burst-promoting activity (mBPA) was determined for B lymphocytes pu rified from spleens of CF-1, C57 BL/6J, B6021-7115, and CAF-1J mice us ing syngeneic and allogeneic bone marrow cultures. Addition of B lymph ocyte conditioned medium (LCM), shed membrane-derived vesicles, or int act plasma membranes prepared from syngeneic murine cells stimulated e rythroid burst-forming unit (BFU-E) proliferation by two- to three-fol d above control levels. BFU-E proliferation was increased by six- to e ight-fold, however, when LCM, shed membrane vesicles, or plas ma membr anes purified from allogeneic B lymphocytes were used as sources of gr owth-stimulatory activity. Bioactivity was immunoprecipitated from det ergent extracts of membranes purified from both allogeneic and syngene ic lymphocytes with a monoclonal antibody that specifically recognizes mBPA, suggesting that the factors expressed by these cells share anti genic determinants. The results indicate that allogeneic effector cell s are a more potent source of mBPA-like molecules than are syngeneic c ells, suggesting that immune mechanisms may be involved in inducing er ythroid growth factor expression at the B cell surface.