Is protein synthesis necessary for the commitment of lymphocyte transformation?

Abstract

WHEN resting lymphocytes are exposed to concanavalin A (con A) they are stimulated to enter the mitotic cell cycle^1,2. As the cells transform, protein synthesis increases markedly prior to DNA replication and they increase in mass some threefold (blast formation)^3,4. That protein synthesis is necessary for lymphocyte transformation has been verified here using anisomycin, an inhibitor of protein synthesis³. The mechanism of anisomycin action on protein synthesis is highly selective; it inhibits peptidyl transferase activity, and hence peptide bond formation, on cytoplasmic (80S) ribosomes. In this study the inhibition of lymphocyte transformation by anisomycin was found to be reversible and this provided a means of examining whether protein synthesis is necessary for the initial commitment of the cells into the mitotic cycle. The experiments described here were designed to test the possibility that cells exposed to con A become committed to transform, even though transformation itself is blocked.