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BACKGROUND: MER2 (RAPH1), the only antigen of the RAPH blood group system, is located on the tetraspanin CD151. Only four examples of alloanti-MER2 are known. We report here two new examples of alloanti-MER2, in women of Pakistani and Turkish origin, one of whom showed signs of a hemolytic transfusion reaction (HTR) after transfusion of 3 units of red cells (RBCs). STUDY DESIGN AND METHODS: Standard serologic methods were used. A monocyte monolayer assay (MMA) was used to assess the potential clinical significance of one of the antibodies. All exons and flanking intronic sequences of CD151 were amplified and sequenced. A homology model for CD151 second extracellular loop (EC2) was constructed based on the crystal structure of CD81. RESULTS: RBCs of both patients did not react with alloanti-MER2, and neither of their antibodies reacted with MER2-negative RBCs. The MMA results suggested that the antibody that appeared to have caused an HTR had the potential to be clinically significant. Both patients were homozygous for a 511C>T mutation in CD151 encoding an Arg171Cys change. This change did not result in any significant structural rearrangement in the protein model. CONCLUSIONS: Two MER2-negative patients with anti-MER2 are homozygous for the same novel mutation encoding an amino acid substitution in the EC2 of CD151. One of the antibodies may have been responsible for an HTR, and crossmatch-compatible RBCs should be recommended for transfusion to patients with anti-MER2.

BACKGROUND: In 1994 during the investigation of a case of hemolytic disease of the newborn, a new lowincidence red cell (RBC) antigen, LOCR, was described. Although the presence of LOCR was associated with altered expression of Rh antigens, its formal assignment to the Rh blood group system did not occur until haplotype and linkage analysis conducted in 2003 provided the necessary proof. The current study was undertaken in an attempt to define the underlying RH mutation in LOCR+ individuals. STUDY DESIGN AND METHODS: Genomic DNA from five unrelated LOCR+ individuals and three Rh-matched control individuals was amplified by polymerase chain reaction with intronic primers flanking all 10 exons of RH. Amplified products were separated on 1 percent agarose gels and isolated for DNA sequence analysis in both the forward and the reverse directions. RESULTS: DNA sequence analysis of the three LOCR+ D‐ individuals revealed a single heterozygous 286G>A nucleotide substitution resulting in a predicted Gly>Ser substitution at amino acid 96. DNA sequence analysis from the two LOCR+ D+ individuals revealed the identical mutation, as well as all of the changes associated with the common RHD gene. CONCLUSIONS: Based on our results, a Gly96Ser substitution in the Rhce polypeptide defines the lowincidence RBC antigen known as LOCR. This same amino acid change has previously been shown to be involved in the Rh:-26 phenotype, which suggests that LOCR and Rh26 are antithetical. Serologic investigations with various Rh:-26 cells and serum samples, however, reveal that only some c+ Rh:-26 phenotypes are LOCR+. ltered expression of primary (D, C, c, E, or e) Rh blood group system antigens in the presence of a low-incidence antigen is typically the first evidence that a “new” antigen is a member of the Rh system. The list of antigens that fall into this group include C w (Rh8), C x (Rh9), E w (Rh11), D w (Rh23), Go a

The Redelberger antigen (Rba) was first discovered in 1974 on the RBCs of a blood donor who was an employee of the Community Blood Center in Dayton, Ohio. The discovery was made as a result of the investigation of a reagent contamination problem. Two examples of the Rba antigen were subsequently identified in the United Kingdom, but no “new”examples have been identified in the United States or Europe. Anti-Rba is a commonly occurring antibody, often found in combination with other antibody specificities, especially in combination with other antibodies to low-incidence antigens. Immunohematology 2006;22:48–51.

G. L. Daniels (Chair), D. J. Anstee, J. P. Cartron, W. Dahr, A. Fletcher, G. Garratty, S. Henry, J. Jorgensen, W. J. Judd, L. K ornstad, C. Levene, M. Lin, C. Lomas-Francis, A. Lubenko, J. J. Moulds, J. M. Moulds, M. Moulds, M. Overbeeke, M. E. Reid, P. Rouger, M. Scott, P. Sistonen, E. Smart, Y. Tani, S. Wendel & T. Zelinski*

Investigation of a mild case of hemolytic disease of the newborn has led to recognition of a ‘new’ low-incidence red cell antigen, WARR (ISBT No. 700.55). Data gleaned from two kindreds, both with Native American heritage, exclude WARR from the MNS, Lutheran, Lewis, Duffy, Kidd, Xg, Chido/Rodgers, Kx and Gerbich blood group systems. Serologic or genetic evidence suggests it is not part of the Kell or Yt systems.

The Glycophorins (GPs = sialoglycoproteins) in erythrocyte membranes from various Black individuals, some of which exhibit the M1, Can, Sj, Tm, Sext and/or Hu antigens, and several Caucasian donors, including pooled fetal red cells, were studied. Using agglutination inhibition assays with GP fractions, GP fragments and chemically modified GPs as well as trypsin treatment of intact red cells, the antigens defined by anti-M1, anti-M+M1, anti-Can and anti-Tm sera were found to be located on the N-terminal tryptic peptide (T2, residues 1-31) of the major GP (GP A = MN sialoglycoprotein). Evidence was obtained that the N-terminal amino-acid residue, NeuNAc and/or (a) different sugar residue(s) are involved in the antigens. Amino-acid sequence and composition analyses excluded an amino-acid exchange within the N-terminal region (residues 1-31) of GP A. Carbohydrate analyses revealed the attachment of GlcNAc residues (up to about five, dependent on the strength of the above-mentioned antigens) to O-glycosidically linked oligosaccharides within the N-terminal portion (residues 1-31) of GP A. As judged from the carbohydrate compositions of peptides, the alteration of the O-glycosidic oligosaccharides is associated with a slight increase of the Gal and Fuc contents and a slight decrease of the NeuNAc level. Analyses of small, secondary cyanogen bromide and V8 proteinase peptides from the N-terminal region of GP A from Blacks, Caucasians and Caucasian fetal cells suggest that the variable attachment of small quantities of GlcNAc (about 0.03 to about 0.2 residues per peptide molecule) accounts, at least in part, for the polymorphisms detected by anti-Can and the original anti-Tm (serum Sheerin). Remarkably, the GlcNAc-containing O-glycosidic oligosaccharides occur only in small quantities, or not all at, within the positions 32-61 of GP A and the glycosylated domains of GP B and GP C.(ABSTRACT TRUNCATED AT 400 WORDS)

A multilaboratory investigation during several years has identified a low incidence antigen JAL on the red cells of 7 propositi. JAL appears to be associated with two unusual Rh complexes, one of which produces a depressed C antigen and the other a depressed c antigen. Family studies strongly suggest that the JAL antigen is encoded by the RH locus. Anti-JAL has been implicated in haemolytic disease of the newborn and is thus considered to be a clinically significant antibody.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder associated with absence of expression of phosphatidylinositol (PI)- linked membrane proteins from circulating hematopoietic cells of multiple lineages. Recent work demonstrated that decay accelerating factor, one such PI-linked protein, bears the Cromer-related blood group antigens. This study demonstrated that other high incidence antigens, including Cartwright (Yta/Ytb), Holley-Gregory (Hy/Gya), John Milton Hagen (JMH), and Dombrock (Doa/Dob), are absent from the complement-sensitive (PNH III) erythrocytes of patients with PNH. The relatively normal, complement-insensitive erythrocytes from the same patients express these antigens normally. Therefore, these antigens most likely reside on PI-linked proteins absent from PNH III, but not PNH I, erythrocytes.

BACKGROUND: Semaphorin 7A (Sema7A), the protein that carries the JMH blood group antigen, is involved in immune responses and plays an important role in axon growth and guidance. Because previous serologic studies on red blood cells (RBCs) suggested a considerable diversity of Sema7A, the present study was designed to elucidate the complex picture of the molecular diversity of this protein. STUDY DESIGN AND METHODS: The JMH antigen status was determined by serology, flow cytometry, and Western blot. Genomic and transcript analysis of SEMA7A was performed by nucleotide sequencing. Recombinant Sema7A proteins were used for genotype-phenotype correlation. A three-dimensional model of Sema7A was generated for topologic analyses. RESULTS: Our studies on 44 individuals with unusual JMH phenotypes and their family members revealed that aberrant Sema7A expression can be an inherited or an acquired phenomenon and is based on reduced surface expression or qualitative changes in Sema7A. These different phenotypes are caused by variations of the SEMA7A gene or seem to be generated by autoimmune-related or RBC lineage-specific mechanisms. The variant JMH phenotypes were related to the presence of missense mutations in SEMA7A, predicting amino acid changes in the semaphorin domain of Sema7A. Sequence analysis of the variant SEMA7A alleles revealed mutations affecting codons 207 and 460/461. Topologic analyses showed that Sema7A polymorphisms were prominently located on the top and bottom of the semaphorin domain, suggesting a functional relevance of these sites. CONCLUSION: These findings provide a basis with which to delineate the various ligand-binding surfaces of Sema7A.

Proteins G and A coated on agarose have been extensively used in affinity chromatography. Protein G will bind to all four subclasses of human IgG and protein A to the subclasses IgG1, IgG2, and IgG4. This IgG binding ability of protein G and protein A has been used in a red cell affinity column technology developed for the detection and identification of IgG red cell antibodies. When serum or plasma is incubated in a microcolumn with red blood cells (RBCs) that express the appropriate antigens, the antibodies become attached to the RBC surface. When the microcolumns are centrifuged, the RBCs pass through a viscous barrier into an active matrix containing proteins G and A. Positive tests adhere at the top of the gel and negative tests pass through, settling to the bottom. This study was undertaken to compare affinity column technology with low-ionic saline solution (LISS) tube tests in a reference laboratory setting. Over a 1-year period, 314 samples were tested in parallel by affinity column technology and by LISS tube technique. Both methods detected antibodies directed at common RBC antigens, high-incidence and low-incidence RBC antigens, and warm-reacting autoantibodies. IgM antibodies were not detected by affinity column technology. Affinity column technology compares favorably with the LISS tube technique for IgG antibody detection and identification.

A survey of sera containing antibodies to multiple low-incidence antigens revealed a variety of patterns of reactions with NFLD+, BOW+, and Wu+ red cell samples. Although NFLD, BOW, and Wu are distinct antigenic determinants (International Society of Blood Transfusion numbers 700.37, 700.46, and 700.13, respectively), their ability to absorb and elute "crossreactive" antibodies indicates a serologic and possibly a genetic relationship among the three.

Concordance of reactions of Wu+ and ‘Hov’+ cells with 153 sera containing multiple specificities to low-incidence antigens indicates that the ‘two’ antigens are identical. This conclusion is confirmed by absorption and elution studies.

For some time, anomalous serological reactions have been observed when the same anti-Swa sera are tested against red cells from different individuals reported as Sw(a+). A comparative collaborative study using the same collection of Sw(a+) cells and anti-Swa sera was undertaken by 4 reference laboratories, and it was found that Swa represents a heterogeneous group of antigens that can be subdivided into two categories. Both categories, Sw(a+) 700:41 and Sw(a+) 700:-41, were shown to be inherited.

Three examples of an antibody were found to be detecting a red cell polymorphism probably identical to MER2. The antibodies were made by Jews originating from India and living in Israel. Two of them were sibs and the third was unrelated. All 3 had kidney disease requiring renal dialysis and regular blood transfusion. In 2 cases the antibodies were detected before dialysis was started and before the patients had been transfused. The human antibodies reacted with red cells of 90% of Israeli blood donors tested. In tests on selected blood donors, 82 English and 56 Israeli, one of the human antibodies gave almost identical reactions to those given by monoclonal anti-MER2. Anomalous reactions were probably due to anti-Bga. Two of the human antibodies completely blocked, and one partially blocked, the reaction of monoclonal anti-MER2 with MER2+ red cells.

Anti-Au, the first example of the antithetical antibody to anti-Au, was identified in the serum of a blood donor who had been transfused 16 years previously. Au has a gene frequency of 0.4326 in an American black population and 0.2994 in a southern English donor population. The expression of Au is suppressed by In(Lu). XS2 also suppresses Auberger antigen expression.