Clinical

IgG subclasses not predictive of hemolysis, hyperbilirubinemia in ABO-heterospecific neonates

Last Updated: 2009-01-19 13:14:34 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Identification of immunoglobulin (IgG) subclasses is not helpful in predicting hemolysis and hyperbilirubinemia in blood group A or B infants born to blood group O mothers, researchers have found.

Direct antibody titer-positive, blood group A and B neonates born to group O mothers may be at risk for hemolysis and hyperbilirubinemia, and IgG1 and IgG3 antiglobulin subclasses may be associated with hemolysis to a greater extent than IgG2 or IgG4, the researchers explain in the January issue of Pediatrics Electronic Pages.

To gauge the predictive value of IgG subclasses for hemolysis and hyperbilirubinemia, Dr. Michael Kaplan from Shaare Zedek Medical Center, Jerusalem, and colleagues studied 82 blood group A or B neonates born to blood group O mothers.

They tested for the presence of IgG subclasses 1 and 3 in umbilical cord blood using a commercially available gel testing technology. By inference, neonates in whom neither IgG1 nor IgG3 were detected were designated IgG2 and/or IgG4.

Of the 82 infants, 18 (22%) were designated IgG1 and none were IgG3; 64 were designated as IgG2 and/or 4.

According to the investigators, the incidence of hyperbilirubinemia -- defined as plasma total bilirubin above the 95th percentile -- was similar between the subgroups.

Corrected carboxyhemoglobin values and corrected carboxyhemoglobin/total hemoglobin ratio as determined by a sensitive gas chromatographic assay - an accurate and reliable index of hemolysis in newborns - were also similar between IgG subclass groups.

In this cohort, "hemolysis and hyperbilirubinemia could not be predicted by this gel technique that enabled identification of these immunoglobulin G subclasses," the investigators conclude. "Other factors will have to be sought for the prediction of hyperbilirubinemia in these neonates."

Pediatrics 2009;123:e132-e137.