Reduced Immune Phagocytosis of Monocytes from Neonates Whose Mothers Produce HLA Antibodies

Abstract
In vivo immune phagocytosis of neonatal monocytes was significantly correlated to the extent of maternal HLA immunization. Monocytes from all 15 neonates of mothers with HLA antibodies show reduced immune phagocytosis. In contrast, this holds true for monocytes from only 6 out of 13 neonates of mothers without detectable HLA antibodies. We infer the hypothesis that maternal HLA antibodies bind to mononuclear phagocytes of the fetus and of the fetal part of the placenta and thus cause inhibition of immune phagocytosis. Thereby, activation and secondary cell or tissue injury will not ensue and rejection of the fetal allograft is prevented in those pregnancies in which maternal alloimmunization occurs.