Cell-cell interactions in in vitro erythropoiesis.

Cell-cell interactions between T and null lymphocytes induce erythropoietin-stimulated differentiation of peripheral blood-derived erythroid progenitors. Monocytes do not inhibit the engagement of this differentiation. By the use of murine hybridoma antibodies, which are uniquely reactive with mature T lymphocytes, the dependence of immature peripheral blood BFU-E differentiation on mature T lymphocytes, or a T cell-conditioned medium is confirmed. Studies with the same antibody show that the more mature and numerous BFU-E found in marrow have no requirement for mature T cells or T cell-conditioned medium. These findings do not preclude the presence in bone marrow of immature T or even non-T cells which may serve as inducers of erythropoietin-dependent erythroid differentiation of mature marrow BFU-E.