RNA Synthesis in Cultures of Normal Human Peripheral Blood

RNA and DNA synthesis were measured in cultures of normal human peripheral blood using tritiated cytidine and thymidine and autoradiographic technics. RNA synthesis preceded DNA synthesis by 24 hours. RNA synthesis occurred predominantly in the large and medium-sized "blast-like" cells, but did occur, to a lesser extent, in the small lymphocytes. RNA synthesis did not occur in the absence of phytohemagglutinin, nor did DNA synthesis. Mechanisms of action of phytohemagglutinin are discussed with particular reference to its possible antigenic nature.