The functional heterogeneity of the lymphocyte.

Rabbit and human lymphocytes were studied for their capacity to respond with blastogenesis and mitosis to various stimuli in vitro. The circulating lymphocytes of two agammaglobulinemic subjects responded to PRA but not to anti-immunoglobulin serum. The cells of all the rabbit lymphoid organs tested (thymus, bone marrow, sacculus rotundus, appendix, lymph node and blood) responded to stimulation with PRA and mitomycin-C inactivated leucocytes. Only the thymocytes failed to respond to stimulation with goat-anti-rabbit immunoglobulin serum (GARIG). They also adsorbed much less GARIG-I125. Pretreatment of normal rabbit lymphocytes with GARIG and complement resulted in a loss of responsiveness to GARIG but not to PRA. Immune rabbit cells pretreated with GARIG could not respond to stimulation with antigen in vitro nor could they synthesize antibodies following their transfer into irradiated recipients. There was an additive effect in vitro between PRA and antigen or PRA and GARIG