Characterization of Lymphocyte Stimulation by Phorbol Related Compounds

Abstract

1 The stimulation of ( 3H)-thymidine incorporation by lymphocytes in response to phorbol and seven other phorbol related compounds was investigated. 2 Lymphocytes from each of a small group of individuals were treated with the test compounds over wide concentration ranges. 3 All the tested compounds, including the most active, 12-0-tetradecanoylphorbol-13-acetate, were far less effective lymphocyte mitogens than the plant lectin phytohaemagglutinin. 4 Inter-individual differences were detected in the maximum response to the phorbols but not in their stimulating potency, as estimated by the concentration producing a half maximal response. 5 The rank order of the lymphocyte stimulating potency of the tested compounds was similar to the rank order of both tumour promoting activity and irritant potency in mouse skin. 6 Lymphocyte stimulation was paralleled equally well by these two mouse skin responses.