Successful antiretroviral therapy has surprisingly meager effects on overall immune function in HIV patients, researchers say. Dr. Christopher G. Lange and colleagues at Case Western Reserve University in Cleveland, Ohio, the University Hospitals of Cleveland, and the Salvador Zubiran National Institute of Nutrition and the National Institute of Respiratory Illness in Mexico City, assessed immune function in patients who achieved viral suppression with highly active antiretroviral therapy (HAART).

Even though CD4 cell counts improved during HAART, immune responses to antigen challenge were not significantly greater than those seen in untreated patients, Lange and coauthors found. Median CD4 cell counts more than tripled as viral loads dropped during HAART, to 483 cells/mL from nadirs of 150 cells/mL, study data showed. However, untreated patients demonstrated significantly higher levels of activated CD4 and CD8 cells.

Moreover, lymphocyte proliferation (LP) and delayed type hypersensitivity (DTH) responses to most antigens were similar in HAART-treated and -naive patients, the researchers said. One exception was HIV Gag antigen, which provoked significantly greater LP responses in HAART-treated patients.

DTH responses to mumps antigens were also augmented during HAART ("Impact of Suppression of Viral Replication by Highly Active Antiretroviral Therapy on Immune Function and Phenotype in Chronic HIV-1 Infection," Journal of Acquired Immune Deficiency Syndromes, 2002;30(1):33-40).

"Thus, HIV-1-infected patients who experienced substantial increases in CD4+ T-lymphocyte counts after suppression of viral replication on HAART had fewer activated lymphocytes and similar immune function when compared with findings in untreated patients with similar CD4+ T-cell counts," Lange and colleagues concluded.

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