Human Immunodeficiency Virus (HIV)-Negative Men Who Have Sex With Men Have Higher CD8+ T-Cell Counts and Lower CD4+/CD8+ T-Cell Ratios Compared With HIV-Negative Heterosexual Men.

Background: We previously reported T-cell senescence to be similar in people with human immunodeficiency virus (PWH) with suppressed viremia (predominantly men who have sex with men [MSM]) and human immunodeficiency virus (HIV)-negative otherwise comparable controls but greater than in healthy blood donors. This led us to compare CD4+ and CD8+ T-cell counts and CD4+/CD8+ ratios between HIV-negative MSM and men who only have sex with women (MSW) and relate observed differences in behavioral factors and infectious exposures, including cytomegalovirus (CMV) infection.

Methods: In 368 HIV-negative MSM and 72 HIV-negative MSW, T lymphocyte phenotyping was performed 3 times biennially. Baseline CMV serology and sexually transmitted infection (STI) incidence and/or STI seroprevalence, sexual, and substance-use behavior data were collected during study visits.

Results: Men who have sex with men, compared with MSW, had higher CD8+ counts (551 vs 437 cells/mm3, P < .001), similar CD4+ counts (864 vs 880 cells/mm3, P = .5), and lower CD4+/CD8+ ratios (1.84 vs 2.47, P < .001). Differences were most pronounced for MSM with >10 recent sex partners and partly explained by higher CMV seroprevalence in MSM.

Conclusions: These findings suggest that factors other than HIV may, in both PWH and certain HIV-negative MSM, contribute to a low CD4+/CD8+ ratio. Whether this, like in PWH, contributes to comorbidity risk in HIV-negative MSM requires further study.