Immune Correlates of Virological Response in HIV-Positive Patients after Highly Active Antiretroviral Therapy (HAART)

Abstract

Correlates of immune reconstitution after highly active antiretroviral therapy (HAART) are not completely understood, in particular as far as viro-immunological discordant responses are concerned. HIV-positive patients on stable HAART for ≥1 year were recruited. Viro-immunological responses were categorized according to positive or negative area under the curve (AUC) variations for HIV plasma viral load (pVL) and CD4⁺ T-cell counts measured at least every 4 months. The following parameters were evaluated: lymphocyte spontaneous apoptosis (LSA), intracellular Bcl-2 expression in both CD4-CD45RA⁺ and CD4-CD45R0⁺, IL-7 and IL-15 plasma concentrations, and lymphocyte TRECs levels. Sixty-one patients were enrolled. A significant inverse correlation was found between CD4⁺ T-cell count and pVL AUC (r = 0.45; p = 0.0003). Patients with pVL response had higher levels of Bcl-2 in CD4-CD45R0⁺ (mean 65,409 MESF vs. 54,018 MESF; p = 0.089) and higher IL-15 (mean 1.34 pg/mL vs. 1.05 pg/mL; p = 0.069, respectively). Higher LSA and lower TRECs levels were found in viro-immunological non-responder patients with respect to those who had viro-immunological response (mean 24.84% vs. 14.89%; p = 0.01, and mean 17,796 copies/10⁶ cells vs. 29,251 copies/10⁶ cells; p = 0.68, respectively). Virological suppression may allow Bcl-2 and IL-15 hyperexpression during incomplete immune-reconstitution phase, while more complete immune reconstitution appeared to be marked by both high TRECs and low LSA levels, possibly indicating both central and peripheral CD4⁺ T-cell repopulations at this stage.