In vitro effects of natural plant polyphenols on the proliferation of normal and abnormal human lymphocytes and their secretions of interleukin-2.

The growth of two human lymphoid tissue derived cell lines, IM-9 and Molt-4 cells together with normal lymphocytes was studied in the presence of several plant natural products. Amongst the 11 test compounds studied, the flavonoids (fustin, taxifolin, phloretin) and the polyphenol tannic acid were potent inhibitors. At concentrations ranging from 10-50 microM they exerted varying degrees of inhibition on Molt-4 cell and normal lymphocyte cell proliferation but not on the non-malignant (IM-9) cells. The order of potency was tannic acid > phloretin > taxifolin > fustin. The IL-2 level was also enhanced in the Molt-4 but inhibited in normal lymphocytes. However, its level remained unchanged in the IM-9 cells. The amount of IL-2 secreted could be directly correlated to the percentage cell growth inhibition for only Molt-4 cells. Interestingly, our findings suggest the possibility of exploiting the natural plant polyphenols for their possible use in the treatment of lymphocyte malignancy.