Interference of anti-M antibody with ABO blood grouping — own experience

Background: Anti-M antibody alloantibody is a fairly common, naturally occurring cold-type antibody.e mostly of the IgM class but may also occur as IgG or IgM with IgG component. It is considered clinically insignificant as it reacts at temperatures below 37°C. IgM class anti-M antibody may be responsible for interference with the standard ABO blood grouping in patients. Material and methods: In this study we focus on the experience of the Reference Laboratory of the Regional Blood Transfusion Center Katowice in detection, identification as well as interference of anti-M alloantibody with ABO grouping. Between January 1st 2022 and June 30th, 2022, the Reference Laboratory performed 1800 consulting and blood grouping tests. The study test pool was divided into 2 groups by age: 4 months–18 years and above 18 years of age. 137 cases of anti-M antibodyalloantibody from the MNS blood group system were detected and identified. In cases of ABO blood grouping-problems, additional procedures were applied such as blood grouping with conventional test tube technique (CTT) at 37°C, use of standard M negative O, A1, B red blood cells and treatment of sera with 2-mercaptoethanol (2-ME) agglutanation test. Results: Anti-M antibody interference with ABO blood grouping was more common for individuals under 18 years of age than in the older patients. Anti-M antibody occured approximately twice as frequently in the IgM class than in the IgG/IgG + IgM class, regardless of age/study group. Conclusions: Anti-M antibody was causing unexpected positive reactions of the study serum with standard red blood cells and the reason of complications in interpretation of results and delay in their the issue/release.