OBJECTIVETo study the alteration of the expression of CD28 on CD4 + T cells in HIV/AIDS patients and observe the dynamics of CD28 expression under highly active antiretroviral therapy (HAART).

METHODSThe expression of CD28 on CD4 + T cells, CD4 counts, and plasma viral load were measured by flow cytometry and bDNA assays in 278 treatment-naïve HIV/AIDS patients and 56 healthy controls. In addition, the evolution of these parameters was assessed in 59 patients who initiated HAART and were followed for 12 months in regular 3-month visits.

RESULTSThe median level of CD28 on CD4 + T cells decreased dramatically in treatment-naïve HIV-positive individuals than in HIV-negative controls (P <0.001). The expression rate of CD28 molecule was positively correlated with CD4 counts (r = 0.484, P < 0.001), and negatively correlated with plasma viral load (r = -0.300, P <0.001). In patients who had received one month of standard HAART, the level of CD28 on CD4 + T cells increased rapidly from 75.0% to 90.0% (P < 0.001). Moreover, there was a negative correlation between the median CD28 expression and the median viral load (r = - 0.829, P = 0.042).

CONCLUSIONSThe level of CD28 expression on CD4 + T cells is down-regulated in treatment-naïve HIV/AIDS patients. HAART can successfully restore the lymphocyte subsets of CD4 + CD28 + T cells. The up-regulation of CD28 expression after HAART may be closely correlated with the suppression of the viral replication.