Altered cord blood γδ T cell repertoire in Nigeria:: Possible impacts of environmental factors on neonatal immunity

Infectious diseases during pregnancy can impact the development of fetal immunity, leading to reduced neonatal resistance to infection and decreased responses to pediatric vaccines. Plasmodium falciparum causes placental infection in low parity pregnant women and is among the pathogens that affect fetal immunity. Recognizing the relationship between malaria and gamma delta T lymphocytes in adults, we asked whether neonatal gamma delta T cells would be altered in malaria-endemic regions as a marker for changes in fetal immunity. Our initial studies compared cord blood gamma delta T cells from deliveries to HIV- mothers in Jos (Nigeria) where malaria is endemic, or in Rome (Italy). We noted substantial differences in the V gamma 2 repertoire for cord blood collected in Jos or Rome; differences were consistent with a negative selection mechanism operating on the fetal V gamma 2 chain repertoire in neonates from Jos. A specific disruption affected the fraction of gamma delta T cells that we expect will respond to Bacille Calmette-Guerin (BCG). Fetal gamma delta T cell depletion might be a mechanism for impaired neonatal immunity and lowered responses to pediatric vaccines. (C) 2008 Elsevier Ltd. All rights reserved.