A new antigen SUMI carried on glycophorin A encoded by the GYPA*M with c.91A>C (p.Thr31Pro) belongs to the MNS blood group system

Abstract

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 α‐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.

DSLK and Kg: Antithetical antigens in the RHAG blood group system, and characterization of anti‐DSLK antibody

“…The constructs were recombined with CSII‐EF‐RfA (RIKEN BioResource Research Center, Tsukuba, Japan) using the Gateway LR clonase II enzyme mix (Thermo Fisher Scientific). Lentiviral particles were prepared as described previously [9]. HEK293 cells were maintained in Dulbecco's Modified Eagle Medium containing 10% foetal bovine serum.…”

“…To confirm the molecules carrying DSLK and Kg antigens, ICFA was performed according to a method described previously [9]. In brief, several different colours of Luminex beads (MicroPlex™ Microspheres, Luminex Japan Co. Ltd., Minato-ku, Tokyo, Japan) were coupled with one of the following mouse monoclonal antibodies: LA18.18 (Sanquin, Amsterdam, The Netherlands) for RhAG; CBC-450 (in-house) for the cytoplasmic domain of GPA; BIII 136 (Santa Cruz Biotechnology, Dallas, TX, USA) for DI; CBC-458 (in-house) for LW; CBC-374 (in-house) for GE and CBC-371 (in-house) for KEL.…”

Prevalence of GP. Mur variant phenotype among Malaysian blood donors

“…The MNS blood group system is highly polymorphic, which comprises 50 distinct antigens. [ 1 2 ] The antigens of the MNS system are expressed in the red blood cell (RBC) membrane on glycophorin A (GPA), glycophorin B (GPB), or hybrids of both and fully developed at birth. [ 3 ] GPA and GPB are encoded by the homologous glycophorin genes GYPA and GYPB , respectively.…”