Allo-anti-M: Detection peaks around 2 years of age, but may be attenuated by red blood cell transfusion

Alloantibody Identification: The Importance of Temperature, Strength Reaction and Enzymes-A Practical Approach

Red blood cell (RBC) alloimmunization and antibodies formation against non-self antigens on red cells may occur after blood transfusion, pregnancies or other exposures. The RBC alloimmunization rate varies from 2% to 6% according to recent studies. The antibody screen is performed to identify or confirm the presence of antibodies in patient's serum or plasma, as a preoperative or pretransfusion test. The antibody identification process and major crossmatch are critical steps of risk management in transfusion medicine. The aim of this article is to describe a flow chart of the antibody identification. I report three educational examples of case studies associated with the negative direct antiglobulin test and clinically significant single and multiple alloantibodies using the gel method, Anti-M, Anti-c and Anti-E, Anti-Jka and Anti-s. Furthermore, I provide a critical analysis of the current literature on the topic. The flow chart of the antibody identification may simplify the process and possibly reduce errors in routine workflow.

Erythrocyte Alloimmunization and Autoimmunization in the Pediatric Population: A Multicenter, Cross-Sectional Study in Central China

Background

Erythrocyte alloantibodies and autoantibodies complicate transfusion. However, the prevalence of erythrocyte alloimmunization and autoimmunization has not been estimated in the Chinese pediatric population. Therefore, we investigated the prevalence of erythrocyte alloimmunization and autoimmunization in the Chinese pediatric population with the aim of developing a reasonable transfusion management policy in children from China.

Methods

This study included 30,603 pediatric inpatients who were admitted to three tertiary hospitals in central China from May 2020 to October 2022. Antibody screening was carried out with a three-cell panel by column agglutination technology, and samples with positive screening were analyzed for antibody specificity with a 16-cell identification panel. Clinical details of the patients were collected to identify associations with antibody formation.

Results

The alloimmunization rate was 0.55% (169/30,603), and the autoimmunization rate was 0.14% (43/30,603). Alloantibodies comprised 80.09% of the antibodies. The most frequent alloantibodies were anti-M (58.77%), anti-E (9.48%), and anti-P1 (4.27%). Autoantibodies comprised 19.91% of antibodies. Age (p = 0.000), sex (p = 0.016), geographical area (p = 0.000), ABO blood group (p = 0.008), and diagnosis (p = 0.000) were independent risk factors for antibody formation. The risk of antibody formation at the ages of 0-28 days and 1-3 months was zero (odds ratio = 0.000). The antibody distribution was significantly different by age (p = 0.000) and diagnosis (p = 0.000).

Conclusion

Repeat pre-transfusion testing for infants less than 4 months of age can be omitted for no risk of antibody formation. MNS system antibodies, especially anti-M, are prominent in younger children, and this decreases with age. Provision of extended phenotype-matched transfusion for Rh system antigens, especially antigen E, is necessary in children to control erythrocyte alloimmunization. The presence of antibodies with high evanescence rates in the pediatric population suggests the pressing need for nationwide shared transfusion records to avoid hemolytic transfusion reactions in children.