Role of RNA in the induction of Thy-1+ phenotype on prothymocytes.

Differentiation of spleen prothymocytes into Thy-1.2+ cells under the influence of thymosin requires transcription of DNA and translation of RNA, as demonstrated by the effects of inhibitors of DNA, RNA and protein synthesis. The lifespan of the induction message for this T cell differentiation appeared to be relatively short (30 to 60 min) in the presence of a reversible inhibitor of protein synthesis. When anisomycin, a protein synthesis inhibitor, was first introduced into the cell suspension, induction was suppressed but it was restored when actinomycin D, a RNA synthesis inhibitor, was added following anisomycin. By flow cytometry, the RNA content was slightly increased in the presence of thymosin and this increase was enhanced by the simultaneous addition of RNA and protein synthesis inhibitors.