title: Association of the p56lck protein tyrosine kinase with the Fc gamma RIIIA/CD16 complex in human natural killer cells.
abstract: The multimeric Fc gamma RIIIA (CD16) complex is expressed on the surface of natural killer (NK) cells and is composed of a 50-70-kDa transmembrane glycoprotein Fc gamma receptor (CD16), the T cell receptor (TCR)-zeta chain, and the Fc epsilon RI gamma chain. Cross-linking Fc gamma RIIIA initiates the rapid tyrosine phosphorylation of multiple substrates including the zeta subunit and causes subsequent cell activation and antibody-dependent cellular cytotoxicity (ADCC). The subunits of the Fc gamma RIIIA complex lack intrinsic protein tyrosine kinase (PTK) activity, suggesting that receptor-induced tyrosine phosphorylation events are mediated by a nonreceptor PTK. We report here that the human Fc gamma RIIIA is complexed with p56lck, a src-family PTK previously found associated with the CD4 and CD8 receptors on T cells. Upon engagement of the CD16 receptor, p56lck is rapidly (within 30 s) and transiently phosphorylated on tyrosine residues. Several Fc gamma RIIIA-associated proteins are identified in immune complex kinase assays including the TCR-zeta subunit, a p70-90 zeta-associated protein (ZAP), p50a (acidic) and p50b (basic), and p56lck. We demonstrate that the src-family protein tyrosine kinase inhibitor, herbimycin A, blocks increased intracellular calcium levels and ADCC caused by CD16 cross-linking on NK3.3 cells. Likewise cross-linking CD16 with the protein tyrosine phosphatase CD45, abrogates CD16-induced calcium mobilization. These data suggest that p56lck is physically associated with Fc gamma RIIIA (CD16) and functions to mediate signaling events related to the control of NK cellular cytotoxicity.
authors.affiliation: Veterans Affairs Medical Center, Amarillo, TX 79106.
authors.forename: J C
authors.initials: JC
authors.lastname: Cone
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.forename: J M
authors.initials: JM
authors.lastname: Trevillyan
authors.forename: J M
authors.initials: JM
authors.lastname: Bjorndahl
authors.forename: C A
authors.initials: CA
authors.lastname: Phillips
mesh_terms: D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects; D016227:Benzoquinones; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003432:Cross-Linking Reagents / Q000494:pharmacology; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology*; D047029:Lactams, Macrocyclic; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D017452:Receptors, IgG / Q000378:metabolism*; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000276:immunology
chemical_list: D016227:Benzoquinones; D003432:Cross-Linking Reagents; D047029:Lactams, Macrocyclic; D011809:Quinones; D017452:Receptors, IgG; D017828:Rifabutin; D000001:Calcimycin; C020754:herbimycin; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D002118:Calcium