RACIAL-DIFFERENCES IN RATE OF CD4 DECLINE IN HIV-1-INFECTED HOMOSEXUAL MEN

Objective: To determine whether racial differences exist in the rate o f CD4 lymphocyte decline in HIV-1-infected homosexual men. Design: Pro spective cohort study. Study population: Non-Hispanic white (n = 321) and black (n = 102) HIV-1-seropositive homosexual and bisexual men wer e recruited from the Baltimore/ Washington, DC metropolitan areas betw een 1984-1985 and 1987-1990, and evaluated semiannually. Main measurem ents: Changes in CD4 lymphocyte count and CD4 percentage over time wer e analysed using linear regression methods for the 271 white and 69 bl ack participants who had at least four semiannual CD4 lymphocyte measu rements. Results: Rate of decline in CD4 lymphocyte count over 6 month s was much slower among black than white seroprevalent men at all leve ls of baseline CD4 count (baseline 201-400x10(6)/l: +0.24 versus -17.7 x10(6)/l; 401-600x10(6)/l: -11.3 versus -23.9x10(6)/l; 601-800x10(6)/l : -15.1 versus -35.2x10(6)/l; > 800x10(6)/l: -4.3 versus -42.7x10(6)/l for black versus white, respectively), although this was only statist ically significant for the lowest and highest strata of baseline CD4 c ount. These racial differences persisted after adjustment for recruitm ent period (1984-1985 or 1987-1990), follow-up duration, age and zidov udine therapy or Pneumocystis carinii pneumonia prophylaxis. Similar f indings were observed among the 70 white and 11 black seroconverters. Black participants were also less likely than a subgroup of white part icipants matched on baseline CD4 lymphocyte count to be HIV-1 p24 anti gen-positive. However, after acid dissociation of samples initially p2 4 antigen-negative, there were no significant differences in the preva lence of p24 antigenemia at enrollment or after 1 year of follow-up. C onclusions: This analysis suggests a more gradual decline in CD4 lymph ocyte count among black than white Americans. The clinical significanc e of and reasons for this are unclear, but the lower prevalence of p24 antigenemia due to immune complexing among black Americans suggests t hat racial differences in the immune response to HIV may exist. Additi onal studies are needed to validate these findings in a larger cohort of non-whites, and to assess their relationship with other measures of cell-mediated immune function.