THE HUMAN NATURAL-KILLER-CELL RECEPTOR FOR MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-I MOLECULES - SURFACE MODULATION OF P58 MOLECULES AND THEIR LINKAGE TO CD3 ZETA-CHAIN, FC-EPSILON-RI GAMMA-CHAIN AND THE P56(LCK) KINASE

The natural killer cell (NK)-specific p58 surface molecules, recognize d by the GL183 and EB6 monoclonal antibodies (mAb), have been shown to represent the putative NK receptor for HLA-C molecules. The interacti on between p58 receptors and HLA-C results in inhibition of the NK-med iated target cell lysis. In this study, GL183(-)EB6(+) clones (Cw4-spe cific), after mAb-induced surface modulation of EB6 molecules, acquire d the ability to lyse the Cw4(+) C1R cells. In NK clones co-expressing both GL183 and EB6 molecules and unable to kill Cw3-protected target cells, the mAb-induced modulation of EB6 molecules resulted both in se lective co-modulation of GL183 molecules and in the lysis of Cw3-trans fected P815 murine cells. In Line with the co-modulation experiments w e also show that the GL183 and EB6 molecules can be co-immunoprecipita ted from GL183(+)/EB6(+) clones after cell lysis in the presence of di gitonin. The p58 receptor also revealed an association with molecules belonging to the zeta family (i. e. CD3 zeta and FceRI gamma chains). Two-dimensional diagonal gel analysis of the p58 complex immunoprecipi tated from polyclonally activated p58(+) NK cells indicated a preferen tial association with CD3 zeta chains either in the form of covalently linked zeta-zeta homodimers or in the form of zeta-gamma heterodimers , while gamma-gamma homodimers were detectable in low amounts. However , p58(+) clones displaying a unique association with gamma-gamma homod imers could also be isolated. Probing the immunoprecipitated p58 compl ex with anti-p56(lck) antibody also revealed an association with this member of the src family. In addition, mAb-mediated signaling of NK cl ones via p58 molecules induced increments of p58/p56(lck) association. However, under the same experimental conditions that induced optimal in vivo tyrosine phosphorylation of the CD16-associated CD3 zeta chain s, no tyrosine phosphorylation was detected in the p58-associated CD3 zeta; chains. In these in vivo experiments neither anti-CD16 nor anti- p58 mAb could induce tyrosine phosphorylation of the gamma chains. Fin ally, the anti-p58-mediated inhibition of the NK cell triggering via C D16 molecules was not accompained by a down-regulation of the tyrosine phosphorylation of the CD16-associated CD3 zeta chains.