Immunologic and virologic response to highly active antiretroviral therapyin the Multicenter AIDS Cohort Study

Objectives: To evaluate prior antiretroviral therapy experience and host ch aracteristics as determinants of immunologic and virologic response to high ly active antiretroviral therapy (HAART). Methods: We studied 397 men from the Multicenter AIDS Cohort Study (MACS) w ho initiated HAART between October 1995 and March 1999. CD4 cell count and HIV-1 RNA responses to HAART were measured at the first visit following HAA RT (shortterm) and extending from the first visit to approximately 33 month s after HAART (longterm). Prior antiretroviral experience was classified in to three groups based on antiretroviral therapy use during the 5 years prio r to HAART. Age, race and host genetic characteristics also were assessed f or their effects on treatment response. Results: Better short- and long-term CD4 cell and HIV-1 RNA responses were observed in the treatment-naive users. Intermittently and consistently expe rienced users did not significantly differ in response. Whereas race did no t independently affect response, among those initiating HAART with > 400 x 10(6) CD4 cells/l, younger age and the Delta 32 CCR5 genotype were associat ed with a better short-term CD4 cell response. There was a suggestion that having the protective CCR5 genotype also was associated with a better long- term CD4 cell response. Conclusion: Immunologic and virologic response to HAART was stronger in ind ividuals who had no prior experience with the antiretroviral therapy agents subsequently included in their initial HAART regimen. Age, level of immune competence and immunogenetics appeared to play a role in the subsequent im mune reconstitution Following use of highly effective HIV therapy. (C) 2001 Lippincott Williams & Wilkins.