Early Life Immunity and Ability to Respond to Vaccines Hindered by Myeloid Derived Suppressor Cells: Implications for Infant HIV Vaccinology

Background: Despite great progress in reducing HIV mother-tochild transmission (MTCT), there are still serious challenges due to ART adherence. Elimination of new childhood HIV infections will likely require an effective infant HIV vaccine. However, development of such a vaccine may necessitate different approaches from the development of an adult HIV vaccine. Young infants respond poorly to infections and vaccines but the basis of reduced immunity is ill defined. Historically the infant's immune system has been regarded as immature. Here, we describe, for the first time, myeloid-derived suppressor cells (MDSC) in healthy infants, a heterogeneous population of immature, activated myeloid cells with immune suppressive function.