The human mixed lymphocyte reaction responder and stimulator capacities of highly purified T- and non-T cells and the role of monocytes.

E-rosette sedimentation with AET treated sheep red blood cells and human lymphocytes provieded a source of highly purified T- and non-T cells. Together with unseparated cells these were tested for responder and stimulator capacities in the mixed lymphocyte reaction, and it was found that the non-T cells were weak, but consistent responders only when T cells were present as stimulators. On the other hand, T-T combinations always exhibited weak proliferation demonstrating that T cells possess stimulator capacities. Adherent cells grown on Petri dishes were found to exert a dual function: as helper cells in low, and suppressor cells in high concentrations.