Search

An example is presented of an IgG1, anti-Lu6, that reacted by indirect antiglobulin test and was capable of destroying antigen-positive red cells in vivo. Two methods for the measurement of red cell survival, 51Cr labeling and flow cytometry, gave the same result: 20 percent of the test dose of Lu:6 red cells was destroyed in the first hour after injection and 80 percent in the first 24 hours. The clinical relevance of the antibody was correctly predicted by an in vitro monocyte monolayer assay. The finding that this example of anti-Lu6 was clinically significant should not be taken to mean that all antibodies directed against high-incidence Lutheran and Lutheran system-related antigens will behave similarly. When such antibodies are encountered, in vivo and/or in vitro studies to assess their clinical significance are necessary before rare blood is used for transfusion.

Red blood cells stored in saline solution for two weeks at 12 C lose some of their Fya, Fyb, and Fy3 antigenicity. At the same time substances with specific inhibitory activity against appropriate Duffy antibodies appear in the saline. Similar changes could not be recognized in time-expired commercial reagent red blood cell samples.

This report describes a healthy blood donor whose red cells have weakened expression of Kell blood group antigens. Kell antigen activity could not be detected by flow cytometric analysis and was demonstrable only by sensitive serologic techniques. As with normal-strength Kell antigens, reactivity could be abolished by treatment with 2-aminoethylisothiouronium bromide (AET). The donor's red cells have Kx antigen activity. Other commonly tested blood group antigens (MNSs, Rh, P1, Lewis, Duffy, and Kidd systems) appear normal. Clinical and serologic examination showed that this case is different from previously described examples of modified Kell expression. The propositus's phenotype has remained unchanged for 19 months, which suggests that it is not a transient condition. However, family studies provide no evidence that it is inherited. A 93-kD protein, which reacted weakly by Western blot with rabbit antibody to Kell protein, was isolated from the propositus's red cells by immunoprecipitation. This finding was not reproduced in subsequent studies, which suggests that the quantity of Kell protein recovered was at the threshold level detectable by the technique used. The red cell phenotype is categorized as Kmod, of which this is the first example reported in a healthy individual.

Anti-Lu 14 has been found in the serum of a gravida 2 pregnant woman who had not been given any blood transfusions. Her husband is Lu:14 but otherwise of common Lutheran blood type. Maternal immunization probably occurred during the first pregnancy. The second child did not inherit the father's Lu14 gene and was not affected by the maternal antibody.

A case of hemolytic disease in a newborn infant caused by anti-Dia is described. The parents are Japanese. The antibody was an IgG of subclasses IgG1 and IgG3, did not bind complement, and gave a 27 percent phagocytosis rate when used to sensitize red blood cells for a macrophage binding assay. The antibody was not detected during antenatal serologic testing. This case suggests the need for reagent red blood cell panels selected to match antibody specificities likely to be encountered in a particular population.

Blood samples from two families and three other unrelated people contain a mixture of red blood cells of two different ABO types. Previously described causes of red blood cell mosaicism have been excluded from responsibility. Other blood group systems are not involved. The phenotypes, which have been designated ABO mos, are inherited through a variant allele at the ABO locus and appear to arise from a change in regulation of an ABO gene of some somatic cells.

An IgG autoantibody with Kx specificity was found in the blood of a 61-year-old white man. The antibody did not cause hemolysis of his own or transfused Kx-positive red cells. The patient is of common Kell blood type and does not exhibit any clinical or hematologic features of McLeod syndrome.

When red cells (RBCs) are treated with papain, one form of the U antigen, which we have named UPS (U papain-sensitive), is almost completely removed or denatured. A second form, UPR (U papain-resistant), remains unaltered on the treated RBCs. Tests on 42 examples of anti-U showed that two contained only anti-UPS, 19 contained only -UPR, and 21 contained separable -UPS and -UPR. In those sera containing both antibodies, anti-UPR was always the stronger of the two. These findings suggest 1) that UPS is located on the Ss sialoglycoprotein (glycophorin B) at a position distal to a papain-sensitive site or that the cleavage point is within the portion of the SGP that comprises UPS, and 2) that UPR is located between the papain-sensitive site and the RBC membrane. The UPS determinant was not denatured by neuraminidase, L-cysteine, trypsin, ficin, or alpha-chymotrypsin, and it was only partially denatured by pronase. The finding that RBCs treated with para-chloromercuribenzoic acid or para-chloromercuriphenyl sulfonic acid did not react with anti-UPR but did continue to react with anti-UPS suggests that the in situ configuration of UPR, but not UPS, is dependent on the presence of one or more disulfide bonds. RBCs of the S-s-U+(weak) phenotype were shown to carry markedly reduced amounts of both UPS and UPR.

An antibody in the serum of a gravida 4, para 3 woman reacted with red cells from two of her children, her husband, and his mother, but with none of more than 2100 reference red cell samples and blood samples from donors. The reactive antigen was inactivated by 2-aminoethylisothiouronium bromide or dithiothreitol-papain treatment. The antigen was immunoprecipitated from paternal red cells with maternal antibody and shown to migrate by sodium dodecylsulfate polyacrylamide gel electropheresis as a single protein of approximately 93,000 daltons. After transfer to nitrocellulose paper by Western blotting, the protein reacted with a rabbit antibody specific for Kell protein. The chemical inactivation and electrophoretic findings were characteristic of Kell group antigens. The reaction with the rabbit antibody establishes that the "new" low incidence antigen was an epitope on Kell group protein and must be coded for by the Kell gene. It has been designated K23.

An 84-year-old woman with intestinal bleeding had marked reduction of red blood cell antigenicity in the Kell system, and a positive direct antiglobulin test caused by auto-anti-Kpb. KX antigen activity of her cell was increased, an observation which supports the belief that KX marks a precursor structure utilized in the normal Kell biosynthetic pathway. It is postulated that reduced Kell antigenicity was an acquired change that resulted from enzymatic degradation, possibly of bacterial origin.

A second example of anti-K19 has been identified in the serum of a black patient immunized by blood transfusions. The antibody was responsible for delayed hemolysis of transfused incompatible red blood cells. The patient's red blood cells are K:--19 but are otherwise of common Kell phenotype. The K19 antigen is closely associated with the Kell blood group although there is, as yet, no pedigree information to confirm that it is produced by the Kell gene. Tests on 10,757 group O blood donors have not revealed any further examples of the K:--19 phenotype.