Human immune deficiency virus (HIV) infection induces platelet activation by direct and indirect mechanisms. Activated platelets express P-selectin (CD62P). Platelet glycoprotein IV (CD36) has been described as a marker of platelet aggregation. We measured platelet activation and aggregation in HIV using a novel whole blood platelet flow cytometry-based assay.
Forty-one (antiretroviral -naïve HIV+ patients and 41 uninfected controls were recruited from a clinic in the Western Cape. Platelet response was evaluated at two concentrations of adenosine diphosphate (ADP) (0.04mM, 0.2mM). %CD62P and %CD36 were used to evaluate platelet function.
%CD62P levels were higher in HIV+ patients (%CD62P 11.33[5.96-29.36] vs. control 2.48[1.56-6.04]; p<0.0001). %CD36 levels were significantly higher in HIV+ patients (%CD36 12.41[6.31-21.83] vs. control 6.04[1.34-13.15]; p=0.0091). HIV+ patients showed higher levels of %CD36 post stimulation with, 0.04mM ADP (43.32 ± 27.41 vs. control 27.47 ± 12.95; p<0.0214) and no significant difference at 0.2mM ADP (HIV %CD36 39.06 ± 17.91 vs. control 44.61 + 18.76; p=0.3277).HIV patients showed a single phase response to ADP.
We describe a novel platelet flow cytometry assay that assesses and discriminates between resting and activated platelets in HIV patients. We also report that, although platelets are significantly activated in HIV, they retain their functional capacity.