Restimulation in Secondary MLC by Autologous Non‐T Cells

Lymphocytes sensitized in mixed leucocyte culture (MLC) were restimulaied with non‐T or complete cells. Cells primed against autologous non‐T cells and restimulated with autologous cells gave responses with the kinetics of a secondary response. In contrast, cells primed against either type of autologous cell responded to restimulation by allogeneic cells with the kinetics of a primary MLC response. Following priming against alloantigens good secondary responses against both complete and non‐T allogeneic restimulators were seen. Restimulation with auto‐logous non‐T colts, but not autologous complete cells, also led to secondary responses. The observation of” different responses to antigens expressed on non‐T autologous lymphocytes, in comparison to complete cells, implies that the secondary MLC involves more than a response against alloantigen. Allogeneic and autologous MLC may he qualitatively different phenomena. the latter representing the recognition of identifying structure's between interacting populations of cooperating cells.