Consumption of anti-D in the erythroblastotic fetus.
BACKGROUND
Maternal serum anti-D is actively transported across the placenta into the fetal blood where it adheres to D-positive erythrocytes. The anti-D coated red cells attach to Fc-receptors on fetal reticuloendothelial cells and are subsequently phagocytosed and hemolysed. It is not known if anti-D is consumed or recirculated in this process. MAIN QUESTION: Is anti-D in the fetus consumed in the hemolytic process in the erythroblastotic fetus and can the consumption be modulated by high-dose immunoglobulins (i.v.IG) given to the mother?


METHODS
Fetal/maternal serum anti-D concentration ratios were calculated for simultaneously taken blood samples from three groups of Rh(D) immunized pregnant women; six women with fetuses who were of Rh(D) negative phenotype, 19 women with fetuses who were Rh(D) positive and received no treatment and, seven women who were treated with i.v.IG because they bore anemic, Rh(D) positive fetuses.


RESULTS
Fetuses with a Rh(D) negative phenotype expressed an increase in fetal/maternal anti-D concentration ratios from 10 to 55% between 25 and 31 gestational weeks, while Rh(D) positive fetuses without i.v.IG treatment had stable values at the 10% level between 24 and 35 gestational weeks. During i.v.IG-treatment of the mothers, Rh(D) positive fetuses showed an increase in ratio from 10 to 30% between 26 and 34 gestational weeks. There was a statistically significant (p<0.001) difference between regression results of the three groups.


CONCLUSIONS
Fetal anti-D is consumed in the hemolytic process and the consumption can be modulated by i.v.IG given to the mother.
Gottvall
T
T
Department of Obstetrics and Gynecology, Faculty of Health Sciences, Linköping University, Sweden.
Selbing
A
A
D004899:Erythroblastosis, Fetal / Q000378:metabolism* / Q000628:therapy; D005260:Female; D005333:Fetus / Q000276:immunology / Q000378:metabolism*; D005865:Gestational Age; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000494:pharmacology / Q000627:therapeutic use*; D007231:Infant, Newborn; D007518:Isoantibodies / Q000097:blood / Q000378:metabolism*; D016014:Linear Models; D011247:Pregnancy; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin
D016756:Immunoglobulins, Intravenous; D007518:Isoantibodies; C061961:RHO(D) antibody; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin