Immunological characterization of anti-Mia, a red blood cell alloantibody, in Taiwan

Background and Objectives: The red blood cell Mi III phenotype is prevalent in Asia, and its corresponding alloantibody, anti-Mia, has been reported to cause haemolytic transfusion reactions and haemolytic disease of the newborn. However, a complete picture of the immunological characteristics of anti-Mia is still lacking. We therefore conducted a systematic study to evaluate the potential clinical significance of this antibody. Materials and Methods: From April 1999 to March 2000, we identified 60 sera containing anti-Mia among pretransfusion samples at a teaching hospital in Taiwan. These antibodies were tested for immunoglobulin class, thermal range and activity in a monocyte monolayer assay. Results: Thirty-four (57%) of the antibodies were immunoglobulin M (IgM), and 15 retained their activity at 37°C. Of those that were immunoglobulin G (IgG), 96% were of subclasses IgG1 and/or IgG3. Monocyte monolayer assay studies showed that 69% (18/26) of the IgG anti-Mia sera were reactive. Conclusions: Our study justifies the implementation of anti-Mia screening in Taiwan.