Social and immunological differences among uninfected Brazilians exposed or unexposed to human immunodeficiency virus-infected partners

Understanding the social conditions and immunological characteristics that allow some human immunodeficiency virus (HIV)-exposed patients to remain uninfected represents an on-going challenge. In this study, the socio-demographic and sexual behaviour characteristics and immune activation profiles of uninfected individuals exposed to HIV-infected partners were investigated. A confidential and detailed questionnaire was administered and venous blood was tested using HIV-1/enzyme immunoassays, plasma HIV-1 RNA levels/bDNA and immunophenotyping/flow cytometry to determine the frequencies of CD4 and CD8 T cells expressing activation markers. The data analysis showed significant differences (p < 0.05) for immune parameters in individuals who were uninfected, albeit exposed to HIV-infected partners, compared with unexposed individuals. In particular, the exposed, uninfected individuals had a higher frequency (median, minimum-maximum) of CD4(+)HLA-DR(+ )(4.2, 1.8-6.1), CD8(+)HLA-DR(+) (4.6, 0.9-13.7), CD4(+)CD45RO(+ )(27.5, 14.2-46.6), CD4(+)CD45RO(+)CD62L(+) (46.7, 33.9-67.1), CD8(+)CD45RA(+)HLA-DR(+) (12.1, 3.4-35.8) and CD8(+)CD45RO(+)HLA-DR(+) (9.0, 3.2-14.8) cells, a decreased percentage of CD8(+)CD28(+) cells (11.7, 4.5-24.0) and a lower cell-surface expression of Fcγ-R/CD16 on monocytes (56.5, 22.0-130.0). The plasma HIV-1 RNA levels demonstrated detectable RNA virus loads in 57% of the HIV-1(+) female partners. These findings demonstrate an activation profile in both CD4 and CD8 peripheral T cells from HIV-1 exposed seronegative individuals of serodiscordant couples from a referral centre in Belo Horizonte, state of Minas Gerais.