Prevalence and specificity of red-blood-cell antibodies in a multiethnic South and East Asian patient population and influence of using novel MUT+Mur+ kodecytes on its detection

Prevalence of GP. Mur variant phenotype among Malaysian blood donors

BACKGROUND AND OBJECTIVE

A number of glycophorin variant phenotypes or hybrid glycophorin variants of the MNS blood group system bear multiple immunogenic antigens such as Mia, Mur, and MUT. In the East and Southeast Asian populations, glycoprotein (GP.) Mur is the most common glycophorin variant phenotype expressing those three immunogens. The aim of this study was to detect MNS system glycophorin variant phenotypes (GP. Mur, GP. Hop, GP. Bun, GP. HF, and GP. Hut) among Malaysian blood donors.

MATERIALS AND METHODS

In this cross-sectional study, 144 blood donors were selected under stratified random sampling. The deoxyribonucleic acid was extracted from whole blood samples, followed by a polymerase chain reaction assay. Sanger sequencing was used to identify the specific MNS variants and then validated by a serological crossmatch with known anti-Mur and anti-MUT.

RESULTS

GP. Mur was identified among Malaysian blood donors with a prevalence of 6.94%, and no other variants of the MNS system were found.

CONCLUSION

The present study substantiates that GP. Mur is the main variant of the MNS system glycophorin (B-A-B) hybrid in Malaysian blood donors. GP. Mur-negative red blood cells must therefore be considered in the current transfusion policy in order to prevent alloimmunization and immune-mediated transfusion reactions, particularly in transfusion-dependent patients.

Identification and Quantification of Anti-Gp.Mur Antibodies in Human Serum Using an Insect-Cell-Based System

Gp.Mur is a clinically relevant antigen of the MNS blood group system that is highly prevalent in several Asian populations. Its corresponding antibody, anti-Gp.Mur, has been implicated in hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. Currently, identifying and confirming anti-Gp.Mur antibody presence in sera via agglutination of a panel of red blood cells (RBCs) is inefficient and difficult to quantify. Using a baculovirus expression system to express Gp.Mur antigen on insect cell surfaces, we have developed a quantitative cell-based system to confirm the presence of anti-Gp.Mur antibody in human serum. We obtained 10 serum samples preidentified as having anti-Gp.Mur antibody and another 4 samples containing noncorresponding antibodies from hospital patients. Insect cells displaying Gp.Mur antigen successfully adsorbed anti-Gp.Mur antibody in the sera and inhibited the RBC agglutination mediated by this antibody. By varying the concentration of Gp.Mur-displaying cells, we could grade levels of RBC agglutination by anti-Gp.Mur antibody. Densitometric analysis further enabled quantitative determinations of hemagglutination inhibition by Gp.Mur-displaying cells. We believe that this cell-based hemagglutination inhibition system greatly improves or supplements existing technology and is a convenient means for accurately identifying and quantifying anti-Gp.Mur antibody.

Erythrocyte Alloimmunity and Genetic Variance: Results from the Collaborative Study of Alloimmunity to Antigen Diversity in Asian Populations (All ADP)

As an East-Asian international study, we evaluated erythrocyte alloimmunity by gender and history of transfusion or pregnancy. In total, data from more than 1,826,000 patients were analyzed, from whom 26,170 irregular erythrocyte antibodies were detected in 22,653 cases. Antibody frequencies in these cases were as follows: anti-E, 26.8%; anti-Le^a, 20.0%; anti-P1, 7.1%; anti-M, 6.4%; anti-Mi^a, 5.6%; anti-c + E, 5.6%; anti-Le^b, 4.6%; anti-D, 2.8%; anti-Fy^b, 2.6%; anti-Le^a+Le^b, 2.5%; anti-Di^a, 2.0%; and others. For pregnant patients, anti-D (12.7%) was statistically more frequent. For transfused patients, anti-E (37.3%), anti-c + E (9.5%), anti-C + e (3.3%) and anti-Jk^a (3.1%) were significantly more frequent.

The prevalence, immunogenicity, and evanescence of alloantibodies to MUT and Mur antigens of GP.Mur red blood cells in a Southeast Asian patient cohort

BACKGROUND

Antibodies to Mi^a , MUT, and Mur are among the most frequently identified alloantibodies in Southeast Asia. Understanding the characteristics of these antibodies in terms of induction and evanescence would aid in optimizing methods for their detection.

STUDY DESIGN AND METHODS

Antibody testing results between the years 2013 and 2015 with relevant patient demographic data and red blood cell (RBC) transfusion history were retrieved. Cumulative alloimmunization incidence and evanescence to MUT and Mur were estimated by Kaplan-Meier analysis in relation to the number of RBC units transfused and time.

RESULTS

Of 70,543 selected patients, 6186 nonalloimmunized subjects with available antibody testing results posttransfusion were identified. Cumulative alloimmunization incidence for MUT increased from 0.12% (95% confidence interval [CI], 0.03-0.21) to 0.63% (95% CI, 0.25-1.01), while for Mur it increased from 0.04% (95% CI, 0-0.09) to 0.42% (95% CI, 0.05-0.79) when a patient was transfused 2 RBC units as compared to 12. Both antibodies had high evanescence rates and at 1 year, anti-MUT and -Mur will be detected in only 45% (95% CI, 35%-57%) and 27% (95% CI, 17%-43%), respectively, of previously positive patients. MUT and Mur immunogenicity was estimated to be 1.7 and 1.2 times higher than E when their rate of evanescence was taken into account.

CONCLUSION

Antibodies to MUT and Mur develop following multiple RBC exposures. Immunogenicity of MUT/Mur and evanescence rates of the corresponding antibodies is higher compared to anti-E. Appropriate selection of antibody screening cells is needed in view of the high prevalence, immunogenicity, and evanescence of the antibodies.

Anti-Mur as the most likely cause of mild hemolytic disease of the newborn

BACKGROUND

Although rare in the United States, anti-Mur is relatively common in Southeast Asia and has been reported to have clinical significance in Chinese and Taiwanese populations.

STUDY DESIGN AND METHODS

The infant was full term and the second child of a Chinese mother and Vietnamese father, presenting with jaundice. He was clinically diagnosed with immune-mediated hemolytic anemia.

RESULTS

The direct antiglobulin test indicated that the infant's red blood cells were coated only with anti-IgG. Anti-Mur was identified in the maternal serum and the neonate's plasma. The father was found to be positive for the Mur antigen. The cause of the infant's hemolytic anemia was determined to be most likely anti-Mur.

CONCLUSION

Since anti-Mur is implicated in causing hemolytic disease of the newborn, it is important to recognize this antibody more commonly found in Asian patients in the United States as the Mur+ phenotype has a higher prevalence in this population.