IgD and the fetal immune response.

IgD was detected in 84% of cord sera at term by an inhibition-of-hemagglutination test, in contrast to low incidences reported earlier. Cord blood IgD and maternal serum IgD values were unrelated to each other, consistent with a fetal origin of the IgD. The cord blood IgD failed to correlate, either directly or inversely, with cord blood IgA or IgM, suggesting that its presence does not reflect fetal synthesis of specific antibody but rather may be developmental.