Lymphocytes, retinoids vitamin

Phorbol esters. Phorbol esters are an interesting class of compounds which are synthesized by plants of the Euphorbiaceae family. (See also the article by Berry and Helms in this vo1-ume.) They promote skin tumors and also affect the immune system. They stimulate some subpopulations of human T-lymphocytes to divide (Kaplan et al., 1982) and alter the activity of natural killer cells (Kolb et al., 1981). The effect may be adjuvantlike, since the phorbol esters have a macrophage-replacing activity in some culture systems (Koretzky et al., 1982). Vitamin A derivatives appear to inhibit the mitogenic activity of phorbols (Skinnider and Giesbrecht, 1981), but it is not clear whether this is related to the immunopharmacological effects of retinoids discussed above. 

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