Universal Detection of Mi(a) Antigen and Frequencies of Glycophorin Hybrids among Blood Donors in Taiwan by Human Monoclonal Antibodies against Mi(a) (MNS7), Mur (MNS10), and MUT (MNS35) Antigens

Glycophorin hybrids such as GP.Mur are common in Southeast Asians. In Taiwan, clinically significant alloantibodies to the GP.Mur phenotype are the most important issue in blood banks. A large-scale screening of glycophorin hybrids in the Taiwanese population is urgently needed to ensure transfusion safety. Four clones of human hybridomas that secrete anti-Mi(a), anti-MUT, and anti-Mur were established by fusing human B-lymphocytes and myeloma cells (JMS-3). The specificity of each monoclonal antibody (MoAb) was characterized. Three MoAbs were applied on an Automated Pretransfusion Blood Testing Analyzer (PK7300/PK7400) for donor screening. Genotyping was performed to determine the detailed subgrouping of glycophorin hybrids. Four MoAbs are IgM antibodies. Anti-Mi(a) (377T) binds to (46)DXHKRDTYA(54), (48)HKRDTYAAHT(57) peptides, and anti-Mi(a) (367T) binds to (43)QTNDXHKRD(51) peptides (X indicates T, M, or K). Anti-Mur is reactive with (49)KRDTYPAHTA(58) peptides. Anti-MUT is reactive with (47)KHKRDTYA(54). A total of 78,327 donors were screened using three MoAbs, and 3690 (4.71%) were GP.Mur, 20 (0.025%) were GP.Hut, and 18 (0.022%) were GP.Vw. When the Mi(a) antigen was introduced as routine screening, the frequency of Mi(a+) among blood donors in Taiwan was 4.66% (67,348/1,444,541). Mi(a) antigen was implemented as a routine blood testing, and the results were labeled on all red blood cell (RBC) units.