• Lymphocyte subsets;
  • fetal immunology;
  • lymphocyte ontogeny

PROBLEM: To determine the effect of labor on lymphocyte subsets in full-term neonates. Method of Study. Cord blood obtained at delivery from full-term neonates, six born vaginally and six born by elective Cesarean section, was analyzed for lymphocyte subsets. Monoclonal antibodies, immunofluorescence, and flow cytometry were utilized to determine the lymphocyte phenotype frequencies in these neonates. These frequencies were compared by mode of delivery and to adult peripheral blood reference ranges using a two-tailed Student's t-test,P<0.05.

RESULTS: A profile of significantly elevated T (CD2, CD3) and helper cells (CD4) and depressed Natural Killer cells (CD16, CD56) is characteristic of term Cesarean section neonates. Significantly depressed frequency of T cells (CD2, CD3) and helper T cells (CD4) and elevated Natural Killer cells (CD16, CD56) is characteristic of vaginally delivered neonates

CONCLUSIONS: The mode of delivery affects the lymphocyte subset frequencies in full-term neonates.