Transfer of maternal specific cell-mediated immunity to the fetus.

The extent of specific cell-mediated immunity was measured in 67 consecutive newborns and their mothers. The stimulation index of blast transformation of the infants' lymphocytes in the presence of purified protein derivative, Candida extract and streptokinase was greater than 2.0 in 54%, 18% and 23% respectively. This was seen only in infants whose mothers' index was also greater than 2.0 to the same antigen. Leucocyte inhibition factor generated from lymphocytes of four babies in the presence of purified protein derivative inhibited migration of indicator cells over 50%; their stimulation index with purified protein derivative was greater than 2.0. Newborns have cell mediated immunity to the same antigens as their mothers, and this wanes during the first few months of life.