375 Innate Immunity in HIV Infection: Effect of HIV Envelope-NK Cell Interactions S Kottilil*, K Shin, A M Planta, J Arthos, A S Fauci Lab of Immunoregulation, NIAID, NIH, Bethesda, MD
Background: We have previously demonstrated that NK cells from HIV-infected individuals are defective in their ability to suppress endogenous HIV replication. We further analyzed the molecular mechanisms involved in NK-cell HIV interactions in vitro using HIV envelopes derived from primary isolates as well as R5 and X4 strains of HIV.
Methods: NK cells from 10 HIV seronegative individuals were purified and used to analyze apoptosis using Annexin V staining, cytotoxicity assay against K562 using PKH-GLE based FACS assay, proliferative response to IL-2 using 72-hr 3H thymidine incorporation assay, CC-chemokine, and interferon-gamma secretion by ELISA and cell surface receptor expression on NK-cells in vitro prior to and after treatment with HIV envelopes derived from R5 and X4 virus strains. Profile of gene expression of purified NK-cells before and after treatment with HIV envelope and purified HIV strains (IIIB and BaL) was analyzed using Affymetrix gene chip based system. This expression was compared with that of NK-cells from viremic and aviremic HIV seropositive individuals (n = 4 each).
Results: Both R5 and X4 envelopes induce apoptosis of NK-cells (mean, 35% and 42%, respectively). Exposure to HIV envelope also suppresses fresh NK-cell cytotoxicity against K562 (mean 33.8% for NK cells alone, 11.8% for X4-treated NK-cells, p = 0.02 and 16.5% for R5-treated NK cells; p = 0.04). Envelope treated NK-cells exhibit markedly reduced proliferative responses to IL-2 (p = 0.02). NK-cells also produced lower levels of cytokines after exposure to X4 and R5 envelopes. This suppression was not reversed by addition of IL-2, indicating impairment in IL-2 mediated signaling pathway. The results of gene chip analyses will be discussed.
Conclusions: HIV envelopes derived from primary isolates suppress generic NK cell functions suggesting that HIV can impair NK-cell function in vivo through envelope NK-cell interactions. The potential mechanisms of these effects will be discussed.