Adverse effect of plasma exchange on anti-D production in rhesus immunisation owing to removal of inhibitory factors

Intensive plasma exchange was used to reduce the maternal anti-D concentration in case of severe rhesus haemolytic disease. Initially the concentration fell from 30 to 4 IU/ml, but after six exchanges it increased to 490 IU/ml despite continued exchanges, and intrauterine fetal death eventually ensued. The increase in the rate of maternal anti-D production coincided with, and may have resulted from, removal of plasma immuno-regulatory factors that inhibited in-vitro lymphocyte functions. These results that the role of plasma exchange in haemolytic disease of the newborn is more complex than simply removing the antibody and that further investigations are needed.