Monocytes are a heterogeneous cell population having specialised functions and differing phenotype. They are a link between innate immune system and adaptive immune system therefore, to identify if immune activation exists in HIV-1 individuals with controlled virema and recovered CD4 T cell counts, we assessed cell surface monocyte activation markers (MAM) within the monocyte subsets.
An eight colour flow cytometry protocol was optimized by evaluating CD45, CD56, NKG2C, CD14, CD16, CD163, CD64 and CD143 in a cocktail and their appropriately matched isotype controls. Utilising this method we assessed MAM in 81 HIV infected individuals from the Western Australian HIV cohort (viremic and non viremic) and 24 normal healthy controls.
The results from this pilot study show little effect of HIV status, CD4 T cell count or age on monocyte subsets however females had lower proportion of classical monocytes than males. The results from MAM analysis did reveal an influence of HIV status on CD64 and CD143 expression on all monocyte subsets (p<0.01). There was no influence of HIV status on CD163 expression on classical or intermediate monocytes however, of interest, the non classical monocyte analysis did revealed an effect of HIV status, but not viral load, on CD163 expression. There was no effect of age or gender with any activation marker on any monocyte subsets. CD4T cell count was associated with viral load and CD64 expression on classical monocytes only.
Monitoring markers of monocyte activation provides a valuable insight into immune activation in HIV individuals. The expression of pro-inflammatory CD16+ monocytes suggests important effects of HIV on innate immunity and this technique appears to be viable and potentially useful for monitoring HIV disease.
