HIV inhibits early signal transduction events triggered by CD16 cross-linking on NK cells, which are important for antibody-dependent cellular cytotoxicity.
Measurement of NK cell cytolytic activity in the setting of chronic viral infection is important for determining viral pathogenicity. Mobilization of LAMP-1 (CD107a) to the NK cell surface is a surrogate marker for cytotoxic granule release and hence, NK cell cytotoxicity. We have developed a convenient, rapid, whole blood flow cytometric assay for measuring CD107a mobilization in response to CD16 cross-linking, a surrogate for NK cell ADCC activity ex vivo, which can be performed using small volumes of patient whole blood. Using this assay, we show that CD107a mobilization, in response to CD16 cross-linking, is triggered in CD56(dim) but not CD56(bright) NK cells, requiring Syk/Zap70 tyrosine kinase activity, and that there is a significant correlation between CD107a mobilization and pSyk/Zap70 in response to CD16 cross-linking. We compared whole blood from treatment-naïve, HIV-infected patients with age- and sex-matched HIV-uninfected control subjects and found a significant reduction in CD16-dependent pSyk/Zap70 (median=32.7% compared with 67.8%; P=0.0002) and CD107a mobilization (median=9.72% compared with 32.9%; P=0.046) in NK cells. Reduction of both correlated strongly with reduced CD16 surface expression on NK cells of HIV-infected individuals (P<0.01). These data suggest that ADCC is inhibited in NK cells from therapy-naïve, HIV-infected individuals at the level of early events in CD16 signal transduction, associated with low CD16R expression, and our method is a useful and reliable tool to detect pathological defects in NK cell degranulation.
Lichtfuss
Gregor F
GF
Centre for Virology, Burnet Institute, Melbourne, Victoria 3004, Australia.
Meehan
Aislin C
AC
Cheng
Wan-Jung
WJ
Cameron
Paul U
PU
Lewin
Sharon R
SR
Crowe
Suzanne M
SM
Jaworowski
Anthony
A
D000328:Adult; D000920:Antibody-Dependent Cell Cytotoxicity / Q000276:immunology*; D019002:CD56 Antigen / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000378:metabolism*; D006678:HIV / Q000276:immunology* / Q000472:pathogenicity; D015658:HIV Infections / Q000276:immunology; D006801:Humans; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology* / Q000821:virology*; D016131:Lymphocyte Subsets / Q000276:immunology / Q000821:virology; D052118:Lysosomal-Associated Membrane Protein 1 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010766:Phosphorylation; D017452:Receptors, IgG / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*; D013997:Time Factors; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism
D019002:CD56 Antigen; D003432:Cross-Linking Reagents; D052118:Lysosomal-Associated Membrane Protein 1; D017452:Receptors, IgG; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human