Induction of B cell differentiation in vitro by bursal epithelium

The inductive capacity of in vitro cultured epithelium of chicken bursa of Fabricius and of its soluble products on B cells precursors was evaluated. The appearance of surface Ia-like antigens was used as an indicator of the early B cell differentiation in vitro. Cultured bursal epithelium as well as soluble substances produced by it were able to initiate B cell development; Ia alloantigens were induced by both syngeneic and allogeneic epithelia. In both cases the induced Ia antigens represented the genotype of the responding cells.