Suggestive evidence for both stimulatory and inhibitory domains on human lymphocytes, as indicated by phospholipid turnover studies with wheat germ agglutinin and other lectins.

Short term effects (1 hours or less) of various lectins on phospholipid turnover in human lymphocytes were studied. As expected, concanvalin A and phytohemagglutinin produced 1,5-4.0 fold increases in incorporation of 32PO4 radioactivity into phospholipids (primarily phosphatidylinositol). Wheat germ agglutinin, a nonmitogenic lectin, not only failed to produce a response but actually inhibited phospholipid turnover, both in the presence and absence of PHA or con A. Since wheat germ agglutinin did not appear to be cytotoxic, as defined by a failure to see changes in vital dye uptake, and other evidence from our laboratory indicates that this lectin also inhibits aminisobutyric acid transport and DNA synthesis in human lymphocytes we would tentatively interpret its negative action as indicating the existence of specific inhibitory domains on the cell surface.