DIFFERENTIAL BASAL PROTEIN-TYROSINE PHOSPHORYLATION IN NATURAL-KILLER(NK) AND T-CELLS - A BIOCHEMICAL CORRELATE OF LYMPHOID FUNCTIONAL-ACTIVITY

Despite the similarities between natural killer (NK) and T cells, thes e lymphocytes have dramatically different functional phenotypes. To id entify potential biochemical parameters that correlate with the ''prim ed'' NK phenotype, we have investigated protein tyrosine phosphorylati on in NK and T cells. Examination of tyrosyl phosphorylation in NK cel ls showed that they have higher levels of phosphorylation than resting T cells. Consistent with this, the concentrations of the tyrosine kin ase inhibitor, herbimycin A, required to inhibit FcR-mediated Ca2+ flu x in NK cells were much higher than those required for inhibition of T cell receptor-mediated Ca2+ mobilization. Differences in phosphorylat ion were not due to purification artifact or explained by differential expression of the prominent lymphocyte src-family kinase, p56(lck) or the protein tyrosine phosphatase CD45. Thus, we have identified high basal tyrosyl phosphorylation as a striking biochemical feature of NR cells that correlates with the unique functions of this subset. (C) 19 96 Academic Press, Inc.