IgG subclasses of anti-A and anti-B antibodies bound to the cord red cells in ABO incompatible pregnancies.
IgG subclasses were determined in 138 A or B infants weighing over 2,500g, born to O mothers. Direct antiglobulin test (DAT) was positive in 43 infants and negative in 95 with anti-A and/or anti-B antibodies detected by heat elution test. In 59 out of 131 infants without ABO hemolytic disease (ABO-HDN), no IgG subclass was detectable. In the 72 others, IgG1 was found in 29/72, IgG2 in 63/72, and IgG3 was not detected. In 7 infants with ABO-HDN, DAT was positive in 4 and negative in 3. In conclusion, in DAT-positive infants without HDN, IgG1 or IgG2 may be bound to erythrocytes, but the amount of IgG1 is too small to cause hemolysis. In DAT-positive ABO-HDN the amount of IgG1 is sufficient to cause hemolysis. In DAT-negative ABO-HDN, IgG3 is responsible for hemolysis, even though undetectable by DAT.
Ukita
M
M
Department of Obstetrics and Gynecology, Kurashiki Central Hospital, Okayama, Japan.
Takahashi
A
A
Nunotani
T
T
Kihana
T
T
Watanabe
S
S
Yamada
N
N
D000017:ABO Blood-Group System / Q000276:immunology*; D004899:Erythroblastosis, Fetal / Q000276:immunology*; D005260:Female; D005312:Fetal Blood / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D007231:Infant, Newborn; D007518:Isoantibodies / Q000276:immunology*; D010789:Phototherapy; D011247:Pregnancy
D000017:ABO Blood-Group System; D007074:Immunoglobulin G; D007518:Isoantibodies