Pregnancy suppresses Mycobacterium tuberculosis-specific Th1, but not Th2, cell-mediated functional immune responses during HIV/latent TB co-infection.

Immunity to tuberculosis (TB) is suppressed due to HIV coinfection and this suppression could further be enhanced by pregnancy. However, the effect of pregnancy on Mycobacterium tuberculosis (M. tuberculosis)-specific immune response during HIV/latent TB co-infection is not well understood. Here we investigated the changes in M. tuberculosis-specific functional Th1, Th2 and antibody responses in pregnant women with HIV/latent TB co-Infection. Pregnancy, concurrent with HIV infection, triggers a substantial suppression of M. tuberculosis-specific IFN-γ responses in a CD4+ T cell count dependent manner with an insignificant change in IL-4 and IgG responses. Conversely, M. tuberculosis-specific IL-10 production was markedly augmented in latent TB infected pregnant women with a lesser extent during HIV co-infection. These findings reveal that pregnancy suppresses anti-mycobacterial protective immune response in a CD4+ T cell count dependent manner during HIV/latent TB co-infection, suggesting a higher risk of developing active TB during pregnancy as a result of failing to control TB infection.