Use of concanavalin A to analyse the mechanism of memory cell differentiation into killer cells.

The renewing by ConA of the cytolytic activity evaluated in a short-term chromium release assay in a population of memory cells obtained in a long-term mixed lymphocyte culture is shown to be largely dependent upon the dose of ConA used; a three staged phenomenon in terms of dose response and kinetics is analysed and suggests that at least for low concentration of ConA (0.5 micrograms/ml) the lectin acts on the same subpopulation and through the same mechanism as the specific antigen, as shown by DNA-synthesis inhibition experiments. Preincubation with ConA at doses giving the best secondary-like response strongly inhibits further response to the primary alloantigen. Experiments using mixtures of ConA and alloantigens as stimulators show that both agents can compete in differentiating memory cells into killer cells. All these data suggest an important overlap of the structures on memory cells which are triggered by ConA or specific antigen.