Nk cell responses among hiv-1 sero negative most at risk individuals in Kampala district.
With more than 30 years of the HIV-1 epidemic, development of an effective vaccine has faced several challenges including but not limited to determining the perfect animal model to predict the effectiveness of an HIV-1 vaccine, continuous mutation of the virus and determining the immune correlates of protection against HIV-1. The existence of HIV-1 seronegative most at risk individuals offers hope that development of an HIV-1 vaccine is plausible. Studies amongst HIV-1 most at risk individuals have shown that Natural Killer (NK) cells may have a positive role in protection against HIV-1 acquisition. In this study, we evaluated HIV-1 specific NK cell responses to HIV-1 peptides among fifty HIV-1 seronegative most at risk individuals. Using a flow cytometric intracellular cytokine assay, results from this study revealed that only 22% (11) out of 50 participant’s PBMCs elicited a response to at least one of the HIV-1 peptides: [HIV-1 subtypes A, B and C (Env, Gag), and HIV-1 subtype B Reg] at a threshold of 0.5% HIV-1 specific peptide response above the background/DMSO, with females contributing to 66.6% of the participant’s responses to the HIV-1 peptides. Our data also showed a significant increase in HIV-1 specific NK cell responses between the baseline and endpoint visits. This observation is suggestive of NK cell memory in some HIV-1 seronegative most at risk individuals against HIV-1 subtypes A and B Env peptides which implies that prior exposure to HIV-1 peptides could result in enhanced NK cell mediated immunity and eventual protection against HIV-1 acquisition.