INVITRO RECOGNITION OF ALLOANTIGENS - NATURE OF RESPONDING AND STIMULATING CELLS

Mixed lymphocyte cultures were incubated in modified Eagle''s Hanks'' amino acid medium with 0.5% mouse serum. The ability of mouse cells to proliferate in mixed lymphocyte culture (MLC) and to generate cytotoxic cells was measured. Thymus cells and splenic T[thymus-derived]-cells were compared with respect to their ability to respond and stimulate in MLC. Spleen cells respond to allogeneic spleen and thymus. Thymus responds to spleen, but fails to respond to thymus. Addition of peritoneal exudate macrophages or adherent spleen cells does not facilitate MLC reactivity or generation of killer cells in allogeneic thymus-thymus cultures. To enrich for B[bone marrow-derived]- or T-cells, spleen cells were filtered through nylon wool columns. Effluent spleen cells respond well to the T-cell mitogen Con A [concanavalin A], but poorly to the B-cell mitogen LPS [lipopolysaccharide] [Escherichia coli]. Column-adherent cells respond well to LPS and poorly to Con A. Addition of mitomycin-treated peritoneal cells enhances the Con A response of effluent spleen, but has no effect on the LPS response of column-adherent cells. Splenic T-cells, obtained by nylon wool column filtration or [rabbit] anti-B-cell serum treatment, respond well in MLC, but are unable to stimulate. Splenic B-cells, obtained by column filtration or anti-.theta. serum treatment, respond poorly but are superior as stimulating cells. Column-filtrated effluent thymus also loses its ability to stimulate spleen. Thymus apparently can stimulate in the MLC because it contains B-cells and/or a subpopulation of stimulatory T-cells.