Revisiting ADCC activity on infected target cells

BIEDMA, M.E.

Estrasburgo

Conferencia; Antibodies beyond binding; 2011

Background: Natural killer (NK) cells keep viral infections under control at the early phase by direct lysis and also by antibody-dependent cellular cytotoxicity (ADCC). Several studies indicated that antibodies with ADCC activity could be induced in HIV-1 infected patients. However, this HIV-1 specific ADCC activity was mainly detected using cell lines. The aim of our study is to analyze ADCC of HIV-1-specific antibodies using primary NK cells and autologous CD4 T-lymphocytes.  Methods: NK cells and CD4 T-lymphocytes were purified from PBMC by magnetic positive selection. Autologous lymphocytes were stimulated before being infected with different R5 HIV-1 strains. NK cells were added to infected CD4-T lymphocytes for 4 hours in the presence of different concentrations of anti-HIV-1-specific antibodies. The percentage of HIV-1-infected CD4 T-lymphocytes was detected by intracellular viral p24 staining. Moreover, ADCC was assessed by the expression of CD107a on NK cells. For each cell donor, a complete immuno-phenotyping of NK cells was performed.  Results: Our results indicated that NK cells are able to lyse HIV-1 infected cells and the addition of HIV-1 specific antibodies (obtained from different cohorts) increased slightly the proportion of lysed cells; indicating that an HIV-1-specific ADCC activity could be detected. A correlation between ADCC activity and phenotyping of NK cells was conducted. The comparison of these data with that previously obtained using cell lines in place to primary cells will allow to deepen in the characterization of HIV-specific antibodies.  Conclusion: We detected ADCC in vitro mediated by primary NK cells on primary CD4T lymphocytes. The results strengthen the possible role of ADCC in HIV-1 inhibition in vivo