Search

Alloagglutinins of M and N specificites with unique characteristics found in normal sera are described. Specific M or N agglutination by these sera occurred only when erythrocytes had been exposed to glucose-containing solutions. Conversion to the form of MN recognized by these sera required incubation of the cells in 1 to 2% glucose buffered to physiological or alkaline pH and was dependent on time and temperature of exposure, occurring in hours at 37 C and in days at 4 C. The sera appeared to be detecting an antigenic structure in which interaction between glucose and the amino group of the N-terminal amino acid of the MN receptor has produced a new specificity, analogous to the action of formaldehyde on N receptors and the resulting N-like structure detected by sera from hemodialysis patients.

A third Finnish En(a-) individual (ERP) with alloanti-Ena has been identified. Subsequent family studies revealed that ERP is distantly related to the 2 previous Finnish En(a-) propositi. Serologically, ERP's erythrocytes were found to be M-N-'N'+S-s+U+En(a-)Wr(a-b-) and were sialic acid deficient. SDS-PAGE studies confirmed that the red cell membranes lacked the MN-sialoglycoprotein, glycophorin-A. ERP's serum contained an IgG antibody which demonstrated two separable specificities, a ficin-sensitive specificity (anti-EnFS) and a ficin-resistant specificity (anti-EnFR), which reacted by the indirect antiglobulin technique. The antibodies were probably pregnancy induced, as ERP had never been transfused. A 51Cr-labelled red cell survival study showed that the antibodies were capable of causing significant destruction of incompatible red cells.

This report presents the first prospectively followed case of hemolytic disease of the newborn due to anti-Jk3 alone. A Samoan woman with known anti-Jk3 was closely monitored during her third pregnancy. Because of elevated delta OD values in the amniotic fluid and rising titer of serum antibody, labor was induced at 36 weeks gestation. The cord red blood cells were coated with IgG, and anti-Jk3 was eluted from the cord cells and the placenta. A family study was done quantitating the expression of Kidd antigens by titrations and scores. Although titrations and scores have been reported to identify cells carrying the silent allele Jk in the heterozygous state, in this family, dosage differences were noted with only 1 of 2 Jk-heterozygous daughters.