Amniotic fluid secretory immunoglobulin A in normal pregnancy and in pregnancy complicated by rhesus isoimmunization.

Amniotic fluid levels of secretory immunoglobulin A (S-IgA) were measured by simple radial immunodiffusion according to the method of Mancini using a monospecific antiserum against the human secretory component. We examined 256 samples from healthy pregnant women and 149 samples from mothers suffering from rhesus isoimmunization. During normal pregnancy amniotic fluid S-IgA increased significantly and showed a loose correlation with the phospholipid levels. This was not observed in pregnancies complicated by rhesus isoimmunization.