Proportions of CD4+, CD8+and B cell subsets are not affected by exposure to HIV or to Cotrimoxazole prophylaxis in Malawian HIV-uninfected but exposed children

Background: As a result of successful PMTCT programs, children born from HIV-infected mothers are now effectively protected from contracting the infection. However, it is not well known whether in utero exposure to the virus and the subsequent exposure to Cotrimoxazole (CTX) prophylaxis affect the cell mediated immune system of the children. This observational prospective study was aimed at determining how CD4(+) T, CD8(+) T and B cell subsets varied in HIV-exposed but uninfected (HEU) children at different ages. Methods: We recruited HEU and HIV-unexposed and uninfected (HUU) children from 6 months of age and followed them up until they were 18 months old. HEU children received daily CTX prophylaxis beginning at 6 weeks of age until when 12 months of age. Venous blood samples were collected 6 monthly and analysed for different subsets of CD8(+) T, B cells and totalCD4(+) T cells. Results: At 6 months of age, HEU children had a lower percentage of total CD4(+) T cells compared to HUU children and a lower proportion of naive CD8(+) T cells but higher percentage of effector memory CD8(+) T cells compared to HUU children. HEU and HUU children had similar proportions of all B cell subsets at all ages. Conclusions: The study showed that the subtle variations in CD4(+) and CD8(+) T cell subsets observed at 6 months do not last beyond 12 months of age, suggesting that HEU children have a robust cell-mediated immune system during first year of life.