Continued CD4 cell count increases in HIV-infected adults experiencing 4 years of viral suppression on antiretroviral therapy

To determine the extent to which HIV-infected patients, including those with advanced immunodeficiency, can reverse peripheral CD4 T-cell depletion while maintaining long-term viral suppression on highly active antiretroviral therapy. Cohort study. Four-hundred and twenty-three HIV-infected patients who initiated HAART prior to 1998 and achieved a viral load 1000 copies/ml. CD4 count changes. Among patients who maintained plasma HIV RNA levels /= 350 x 10(6)/l, respectively (all gains were significantly greater than zero; P < 0.05). Among those with a pre-therapy CD4 count of < 50 x 10(6)/l, 88% achieved a CD4 cell count of >/= 200 x 10(6)/l and 59% achieved a count of >/= 350 x 10(6)/l by year 4. Factors associated with increased CD4 cell count gains from month 3 to year 4 included lower pre-therapy CD4 cell count, younger age, female sex, and infrequent low-level viremia (versus sustained undetectable viremia). Most patients who achieve and maintain viral suppression on HAART continue to experience CD4 T-cell gains through 4 years of therapy. The immune system's capacity for CD4 T lymphocyte restoration is not limited by low pre-therapy CD4 counts.