Cell-mediated immunity to microbial antigens in mother and child.

We have looked at evidence for the transplacental passage of cell-mediated immunity in man. The lymphocyte response of mother-neonate pairs was assessed to non-specific mitogens, allogeneic cells, and to microbial antigens. Although six mothers were known to be chronic carriers of Herpes simplex virus only one of their neonates responded to this viral antigen. On two occasions a lymphocyte response was induced in cord blood by antigens to which the mother did not respond. This paradox remains unexplained. We suggest that the relative immunity of the neonate to some infectious diseases does not depend on the transplacental passage of cellular immunity.