Abstract
NK cell receptors and HLA molecules are intimately involved in the immune response against viral infections. The killer immunoglobulin-like receptors (KIRs) on NK cells regulate NK cell responses via the recognition of their particular HLA class I ligands. At the genomic level, both genetic systems are polymorphic and have recognised haplotypes, which adds complexity to their interaction. Previously, we and others have shown the association of HLA class I with HIV progression. Recently, the Carrington group observed a synergistic effect involving the activating KIR3DS1 gene and HLA-B Bw4-80Ile on the rate of depletion of CD4+ T cells.
To further investigate the relationship between the two genetic systems, we examined changes in viral load in 249 pre-treatment patients from the Western Australia HIV cohort. Genetic variants known to affect HIV progression including HLA-Bw4-80Ile but not KIR3DS1 were associated with differences in HIV-1 viral load set point. When we examined only those patients with known seroconversion dates, we found that the presence of the KIR3DS1 gene was associated with more rapid decline in the proportion of CD4+ T cells (p=0.01) but were unable to show a KIR3DS1 and Bw4-80Ile interaction. The presence of other KIR genes (viz KIR2DS2, KIR2DL2 and KIR2DS1), all found on KIR B group haplotypes, were also associated with a more rapid progression, whilst some KIR genes found the A haplotype with delayed progression
We suggest that multiple KIR genes influence outcome in HIV infection. Further analyses of KIR haplotypes is needed to understand the complex interactions between KIR genes and their ligands in driving NK cell responses to HIV.