On the identity of lymphoid cells that stimulate the rat MLC and produce active enhancement.

The preimmunization of 10(7) Brown Norway (BN) rat lymphoid cells i.v. 1 week before (Lew X BN) F1 to Lewis renal grafting causes a state of immunologic enhancement. The BN lymphoid cells responsible for producing enhancement are the same cells that are capable of stimulating Lewis T cells in one-way MLCs. Thus active enhancement requires immunity to LD antigens, since SD +, LD- BN cells do not create a vigorous enhanced state.