English Polski
Vol 17, No 1 (2024)
Research paper
Published online: 2024-03-29

open access

Page views 395
Article views/downloads 119
Get Citation

Connect on Social Media

Connect on Social Media

Problems with ABO blood group typing associated with the presence of anti-M alloantibodies of the MNS system - own experience

Barbara Sowa1, Michał Kunysz1
Journal of Transfusion Medicine 2024;17(1):7-12.


Anti-M alloantibodies are fairly common, naturally occurring cold-type antibodies. They are typically in the IgM class, but can also occur as IgG or IgM antibodies with an IgG component. They are usually not active at 37°C and therefore are considered clinically insignificant. IgM class anti-M antibodies can cause deviations from the classic ABO blood group typing scheme in patients samples. This study analyzes the experience of the Pracownia Konsultacyjna of the Regionalne Centrum Krwiodawstwa i Krwiolecznictwa in Katowice related to the detection and identification of anti-M alloantibodies and blood group typing issues. From January 1, 2022 to June 30, 2022, 1800 antibody screening or indentification and blood group tests were performed. The analyzed pool of studies was divided into two age groups: from 4 months to 18 years and over 18 years old. In 137 cases, anti-M alloantibodies from the MNS system were detected and identified. In cases where there were problems with blood group typing, additional procedures were used, such as: blood group determination using tube technique at 37°C, use of standard red blood cells A1 and B without M antigen, and treatment of the tested serum with 2-ME reagent. Anti-M antibodies pose a greater problem in blood group typing in individuals under 18 years old than in older patients. They occur approximately 2 times more frequently in the IgM class than in the IgG/IgG+IgM class, regardless of the age of the study group. They cause unexpected positive reactions of the tested serum with standard red blood cells, making it difficult to interpret the results obtained and delaying the release of the blood group result.

Article available in PDF format

View PDF (Polish) Download PDF file


  1. Reid ME, Lomas-Francis C, Olsson ML. The Blood Group Antigen Facts Book. Academic Press, London. ; 2012: 53–62.
  2. ISBT https://www.isbtweb.org/resource/002mnsalleles.html.
  3. Datta SS, Basu S. Importance of Clinically Significant Anti-M Antibody in Hematopoietic Stem Cell Transplantation. Indian J Hematol Blood Transfus. 2016; 32(Suppl 1): 208–210.
  4. Fabijańska-Mitek J. Immunohematologia. Grupy krwi i niedokrwistości. Fundacja Pro Pharmacja Futura; Warszawa. ; 2018: 60–65.
  5. Kuśnierz-Alejska G. Częstość występowania poszczególnych fenotypów i antygenów układu grupowego MNS w populacji polskiej. Acta Haematologica Polonica. 2000; 31(3): 273–278.
  6. Tamai Y, Ohto H, Yasuda H, et al. Pediatric RBC Alloimmunization Consortium. Allo-anti-M: Detection peaks around 2 years of age, but may be attenuated by red blood cell transfusion. Transfusion. 2021 Sep. ; 61(9): 2718–2726.
  7. Fabijańska-Mitek J, Bochenek-Jantczak D, Grajewska A. Badania immunohematologiczne w transfuzjologii - kompendium. Fundacja Pro Pharmacia Futura; Warszawa. ; 2023: 49–50.
  8. Obwieszczenie Ministra Zdrowia z 17 lutego 2021r. w sprawie ogłoszenia jednolitego tekstu rozporządzenia Ministra Zdrowia w sprawie leczenia krwią i jej składnikami w podmiotach leczniczych wykonujących działalność leczniczą w rodzaju stacjonarne i całodobowe świadczenia zdrowotne.
  9. Ulotka odczynnika 2-ME, producent RCKiK w Katowicach; https://odczynnikiserologiczne.pl/oferta/odczynnik-2-me-roztwor-do-roznicowania-przeciwcial-klasy-igm-i-igg.
  10. Das R, Dubey A, Agrawal P, et al. Spectrum of anti-M: a report of three unusual cases. Blood Transfus. 2014; 12(1): 99–102.
  11. Makroo RN, Arora B, Bhatia A, et al. Clinical significance of antibody specificities to M, N and Lewis blood group system. Asian J Transfus Sci. 2014; 8(2): 96–99.
  12. Shah SP, Kalgutkar SM, Sawant RB, et al. Anti-M antibodies: Biphasic (reactive at room temperature and at 37°C): A case series. Asian J Transfus Sci. 2016; 10(2): 159–160.
  13. Tondon R, Kataria R, Chaudhry R. Anti-M: Report of two cases and review of literature. Asian J Transfus Sci. 2008; 2(2): 81–83.
  14. Ferdowsi S, Mohammadi S, Ahmadnezhad M, et al. Anti-M antibody and ABO blood grouping discrepancy: a report of three cases with review of literature. Hematol Transfus Cell Ther. 2022; 44(2): 288–290.
  15. Mathur A, Dontula S, Jagannathan L. An unusual case of a potentially clinically significant anti-M antibody in a healthy male blood donor without any history of blood transfusion. Blood Transfus. 2011 Jul. ; 9(3): 339.
  16. Khalid S, Dantes R, Varghese S, et al. Naturally occurring anti M complicating ABO grouping. Indian J Pathol Microbiol. 2011; 54(1): 170–172.

Journal of Transfusion Medicine