Anti-GYPA monoclonal antibody

BACKGROUND MNS is one of the highly polymorphic blood groups comprising many antigens generated by genomic recombination among the GYPA, GYPB, and GYPE genes as well as by single-nucleotide changes. We report a patient with red blood cell (RBC) antibody against an unknown low-frequency antigen, tentatively named SUMI, and investigated its carrier molecule and causal gene. STUDY DESIGN AND METHODS Standard serologic tests, including enzyme tests, were performed. Monoclonal anti-SUMI-producing cells (HIRO-305) were established by transformation and hybridization methods using lymphocytes from a donor having anti-SUMI. SUMI+ RBCs were examined by immunocomplex capture fluorescence analysis (ICFA) using HIRO-305 and murine monoclonal antibodies against RBC membrane proteins carrying blood group antigens. Genomic DNA was extracted from whole blood, and the GYPA gene was analyzed by polymerase chain reactions and Sanger sequencing. RESULTS Serologic screening revealed that 23 of the 541,522 individuals (0.0042%) were SUMI+, whereas 1351 of the 10,392 individuals (13.0%) had alloanti-SUMI. SUMI antigen was sensitive to ficin, trypsin, pronase, and neuraminidase, but resistant to alpha-chymotrypsin and sulfydryl-reducing agents. ICFA revealed that the SUMI antigen was carried on glycophorin A (GPA). According to Sanger sequencing and cloning, the SUMI+ individuals had a GYPA*M allele with c.91A>C (p.Thr31Pro), which may abolish the O-glycan attachment site. CONCLUSIONS The new low-frequency antigen SUMI is carried on GPA encoded by the GYPA*M allele with c.91A>C (p.Thr31Pro). Neuraminidase sensitivity suggests that glycophorin around Pro31 are involved in the SUMI determinant.

The short tandem repeat systems (STRs) HumCD4 (CD4), HumTH01 (TH01) and HumFIBRA (FGA) were amplified by the polymerase chain reaction (PCR) on blood samples from 100 unrelated Yemenians and 100 unrelated Egyptians. PCR products were separated on native horizontal discontinuous gel electrophoresis followed by silver staining. The distribution of observed phenotypes did not deviate from Hardy-Weinberg equilibrium. While significant differences between both Arab populations and an European population from Austria were found at all loci, differences between the Egyptian and the Yemenian samples were found only for CD4. In a number of verified Austrian families (TH01: 426 meioses, CD4: 275 meioses, FGA: 144 meioses) no mutations were found. The observation of a TH01 allele consisting of 4 repeats was confirmed by sequencing. Moreover we report the structure of a TH01 allele 6.3 observed in a Hungarian Caucasian population.