601b    

Background:  Assesment of of multiple immunovirologic parameters may be useful in determining optimal combinations of antiretrovirals.

Methods:  We enrolled 76 HIV-infected naive patients (66 male, 9 female; 28 injecting drug users [IDU]; 15 men who have sex with men [MSM], 33 heterosexual) in a study to compare different antiviriral regimens (zidovudine [AZT]/didanosine [ddI]/abacavir [ABC]; AZT/lamivudine [3TC]/ABC; AZT/ddI/efavirenz [EFV]; AZT/3TC/EFV; AZT/ddI/indinavir+ritonavir [IDVr], and AZT/3TC/IDVr). Median CD4 count and viremia at baseline were 217/mm³ and 238,301 copies/mL, respectively. Quantitative (CD4 counts) and qualitative (PHA-stimulated ³H thymidine incorporation and cytokine production) immunologic parameters were measured at baseline and after 1 and 6 months of therapy.

Results:  All regimens resulted in increases in CD4 counts and suppression of HIV plasma viremia. Median CD4 count at 6 months was significantly better in ABC-treated patients than in all other groups, and was also significantly more solid in 3- vs 4-drugs-treated patients (median CD4 count:  3 drugs = 373 CD4/mm³; 4 drugs = 246 CD4/mm³; p = 0.01). The best suppression of HIV viremia (all patients with > 50 copies/mL) was observed in AZT/3TC/ABC patients. PHA-stimulated ³H thymidine incorporation as well as interferon-γ and interleukin-2 production at 6 months were significantly better in patients using 4 drugs (AZT/ddI/IDVr and AZT/3TC/IDVr) and, among the 3-drug combinations, in AZT/3TC/EFV-treated individuals.

Conclusions:  These results suggest that ABC-containing regimens are associated with the highest CD4 counts and the strongest suppression of HIV plasma viremia, whereas boosted PI-containing regimens have a more robust effect on functional immune parameters after 6 months from starting thepaphy in drug-naive patients.

Keywords: antiretroviral therapy; immunology; cliniclal benefit