Differentiation of thymocytes: evidence that induction of the surface phenotype requires transcription and translation.

Induction of thymocyte differentiation requires transcription of DNA and translation of RNA but not replication of DNA. This was determined in vitro by studying the effects of cytosine arabinoside, hydroxyurea, actinomycin D, camptothecin, cordycepin, cycloheximide, and puromycin on the induction by thymopoietin of thymocyte differentiation, measured by the acquisition of the differentiation allo-antigens TL and Thy-1 by and inducible fraction of mouse spleen cells. This requirement for transcription does not establish whether the new mRNA represents transcripts of structural genes for the thymocyte allo-antigen markers; an answer to this question awaits the results of further experiments.