The need for transcription and translation for differentiation of bone marrow cells by thymic factors in man.

1. Two small populations of human marrow cells are differentiated to cells bearing T-cell markers by Thymosin F3 or F5. 2. Analysis with metabolic inhibitors indicates that transcription and translation of RNA are needed for induction of T cell markers (layer III). 3. a) At 4 hours incubation RNA synthesis is enhanced in layers III, IV and V and inhibited in layers I + II. b) At 20 hours incubation RNA synthesis is markedly enhanced in all cell layers. 4. a) At 5 hours incubation protein synthesis is suppressed in layers I + II and III, but not in IV and V. b) At 20 hours incubation protein synthesis is markedly increased only in layer III.