Lymphocyte transformation in vitro. III. Mechanism of stimulation in the mixed lymphocyte culture

In view of the correlation between the mixed lymphocyte culture and the HL-A locus, experiments were performed to determine whether the reactivity in the mixed lymphocyte culture is elicited by the HL-A antigens as such.

Fresh lymphocytes were mixed with either allogeneic fibroblasts or allogeneic lymphocytes treated with various metabolic inhibitors or by heating which abolishes their capacity to tranfsorm in vitro.

No stimulation of the normal untreated lymphocytes was observed in any of these mixed cultures.

However, the HL-A antigens 4b and 7b were not affected quantitatively by this treatment as determined serologically.

The conclusion is drawn that mixed lymphocyte culture reactivity is not merely a reaction to HL-A antigens, and the consequences of this are discussed.