Background: Natural killer cells are crucial effector cells of the immune response to viral infections including HIV. It mediates cytotoxicity and cytokine production which have anti-HIV activities. Besides, HIV provides evading strategies such as by expansion of rare NK cell subsets and alteration of surface NK cell markers. However, limited number of studies are done on inhibitory/activating receptors, markers of activation, maturation and delayed HIV progression in Africa particularly Ethiopia.

Objective: To assess subsets, markers of activation, maturation and associated with slow progression of HIV on NK cells among HAART naïve HIV patients and healthy controls (HC).

Methods: A cross sectional study was conducted in 15 HAART naïve HIV patients and 15 HC using convenient sampling technique. Whole blood was collected and stained with CD3, CD16/CD56, CD16, CD56, KIR3DL1/S1, CD8, NKG2C, CD2, CD7, CD57 and HLA-DR. The sample was acquired on a FACS Canto II flowcytometry and analyzed by Flow Jo software. Mann-Whitney U-test with JMP software was used for statistical analysis of the data. Statistical significance was set at P value < 0.05.

Result: The median fluorescent intensity of CD16/56 on NK cells were significantly decreased in HAART naïve HIV patients compared to HC. The frequency of CD8⁺ NK cells were also reduced and are inversely correlated with HIV viral load. From lymphocytes, CD56^bright and CD56^dim NK cell subsets were significantly reduced in HAART naïve HIV patients, respectively. Within total NK cells, CD56^dimsubsets are still reduced and the CD56^-ve subsets are expanded in HAART naïve HIV patients. The CD56^bright subsets further showed lower frequency in CD8 and NKG2C expression among HAART naïve HIV patients relative to HC. However, the frequency of KIR3DL1/S1⁺ CD56^bright and HLA-DR⁺CD56^bright NK cell subsets were expanded in HAART nave HIV patients compared to HC.

Conclusion: This study showed that HIV infection is associated with altered subsets distribution, varied expression of markers associated with slow progression, activation, and high potency particularly on CD56^bright NK cell subsets. However, further follow-up and functional study need to be conducted.

Key word: NK cell markers, HAART naïve HIV, Ethiopia