Human immunodeficiency virus-exposed but uninfected infants (iHEU) display altered immunity and are at increased risk of infection. We previously reported that iHEU have decreased maternal microchimerism (MMc)-maternal cells transferred to the offspring in utero/during breastfeeding. We quantified MMc in T-cell subpopulations in iHEU and HIV-unexposed infants (iHU) to determine whether a selective deficiency in MMc contributes to altered cellular immunity. Across all infants, MMc levels were highest in CD8+ T cells
however, the level of CD8+ T-cell MMc was lower in iHEU versus iHU. In limited functional studies, we did not identify cytomegalovirus-specific MMc during infant primary infection.