Lymphocyte stimulation with phorbol myristate acetate in atopic and non-atopic individuals. 
Phorbol myristate acetate (PMA) was found to be a potent stimulator of DNA synthesis in human whole blood cell cultures.  Stimulation with pokeweed mitogen was strongly enhanced by addition of PMA-activated cells.  PMA responsiveness varied with age, being low or absent in newborns and very pronounced in adults.  In atopic children, PMA responsiveness was normal or increased.  The ratio of phytohemagglutinin to PMA responsiveness was significantly reduced in cultures from such children.  This finding would be compatible with the hypothesis of a relative suppressor cell deficiency in atopic disease.  The results of tests designed to detect suppressor and helper cell activity, added further support to this hypothesis.