title: Evidence for the protective effect of maternal FcR-blocking IgG alloantibodies HLA-DR in Rh D-haemolytic disease of the newborn.
abstract: In cases of Rh D alloimmunization, strong results in the antibody-dependent cell-mediated cytotoxicity (ADCC) assay (> 80% lysis as compared to that of the standard anti-D serum) are indicative of severe hemolytic disease to occur in the newborn (HDN). However, discrepant cases were found in which the maternal anti-D gave strong ADCC results and the newborns had no or only mild hemolysis. In the majority of these cases the mother had produced monocyte-reactive IgG alloantibodies, mostly with HLA-DR specificity. Such antibodies may be capable of blocking FcR-mediated functions of the fetal MPS, and it has been postulated that they inhibit destruction of anti-D-sensitized red cells. We here describe 2 families in which such discrepancies were noticed. In 1 family, in spite of ADCC results of > 80%, the Rh D-positive second child was born without signs of hemolysis. However, the Rh D-positive third child suffered from very severe hemolytic disease. The mother had produced monocyte-reactive HLA-DR antibodies in the second pregnancy which, however, did not react with the cells of the third child. In the other family, the severely Rh D-alloimmunized mother had lost her fourth child because of intrauterine death due to HDN. The Rh D-positive fifth child was born with only mild HDN and only in this pregnancy had the mother produced such antibodies. These 2 case histories give further evidence that maternal monocyte-reactive alloantibodies, in both these cases directed against HLA-DR antigens, can protect the Rh D-positive child against hemolytic disease in case of severe Rh D alloimmunization.
authors.affiliation: Department of Immunohematology, Central Laboratory of the Netherlands, Red Cross Blood Transfusion Service, Amsterdam.
authors.forename: M C
authors.initials: MC
authors.lastname: Dooren
authors.forename: I L
authors.initials: IL
authors.lastname: van Kamp
authors.forename: H H
authors.initials: HH
authors.lastname: Kanhai
authors.forename: J B
authors.initials: JB
authors.lastname: Gravenhorst
authors.forename: A E
authors.initials: AE
authors.lastname: von dem Borne
authors.forename: C P
authors.initials: CP
authors.lastname: Engelfriet
mesh_terms: D004899:Erythroblastosis, Fetal / Q000276:immunology*; D005260:Female; D006684:HLA-DR Antigens / Q000276:immunology*; D006801:Humans; D007231:Infant, Newborn; D007518:Isoantibodies / Q000097:blood*; D008297:Male; D008431:Maternal-Fetal Exchange; D009000:Monocytes / Q000276:immunology; D011247:Pregnancy; D011961:Receptors, Fc / Q000276:immunology*; D012204:Rh-Hr Blood-Group System / Q000097:blood*
chemical_list: D006684:HLA-DR Antigens; D007518:Isoantibodies; D011961:Receptors, Fc; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen