Background:  The course of AIDS progression and levels of HIV plasma viremia are known to be different between racial groups. This may be related to immune response, and immune response genes may differ in frequency or type by ethnic group. There have been only a limited number of studies comparing immune responsiveness between groups of HIV infected subjects with different racial backgrounds. Here, we compare the magnitude and breadth of HIV-specific T-cell immune responses between Hispanic and black HIV-infected children, closely matched by age, viral load, and/or CD4 percentage.

Methods:  Vertically infected black and Hispanic subject samples were matched for age, viral load, and/or CD4 percentage (n = 21 pairs). HIV-specific T-cell responses were measured using cryopreserved PBMC samples taken from HIV-infected pediatric subjects, age range 1 to 17 years (median age = 9). A cytokine enhanced ELISpot assay was used to measure IFN-g responses after stimulation with HIV consensus peptides from Gag, Nef, and Tat. In order to determine the relative influence of ethnicity, gender, age, HIV-1 RNA levels and CD4⁺ T-cell count on HIV specific Gag, Nef, and Tat T-cell responses, we performed linear regression analyses. HIV-1 RNA levels were log₁₀ transformed prior to analysis. The SAS System Version 8.2 for Windows (SAS Institute, NC, USA) was used to perform all statistical analyses.

Results:  A multivariable linear regression model revealed that, after adjustment for CD4⁺ T-cell count, age in years, and log₁₀ HIV-1 RNA levels, Black children demonstrated significantly higher Gag responses (on average at least 475 spot-forming units (SFU) higher for blacks, p = 0.015) than Hispanic patients. Higher HIV-1 RNA levels tended to be associated with greater Gag responses but did not reach statistical significance (169 SFU higher for each 1 log HIV-1 RNA levels, i>p  =  0.07). No other included terms approached statistical significance. There were trends for higher Nef and Tat responses in blacks as compared to Hispanics, but they did not reach statistical significance. The higher responses in Black children were marked by robust IFN-g responses in black females near the age of puberty.

Conclusions:  These data indicate that black children infected with HIV mount a significantly higher HIV-specific immune response as compared to age and disease matched Hispanic children. Of added interest is the high immune response from black females near the age of puberty.

Keywords: Race; T cell; Gender