Abstract: Objective To analyze the composition and frequency distribution of mixed antibodies in the Chinese population, evaluate the feasibility of screening compatible donors for each mixed antibody combination, and propose recommendations for transfusion strategies in patients with multiple alloantibodies. Methods Data from irregular antibody-positive cases identified in our laboratory and reported in domestic literature were collected and analyzed to determine the specificity combination spectrum of mixed antibodies. Antigen frequency data of blood group systems from various regions in China were systematically retrieved and pooled using a weighted method. The expected probability of finding compatible phenotypes for each mixed antibody combination was then calculated. Two thresholds (≤1/50 and≤1/200) were set to grade the difficulty of blood matching. Results A total of 20 069 irregular antibody-positive cases were included, among which 92 distinct mixed antibody combinations were identified (677 cases, 3.37%). Mixed antibodies were predominantly composed of RhCE system antibodies combined with antibodies from other systems. Seven combinations (69 cases, 10.2% of mixed antibodies) yielded expected compatibility probabilities between 1/50 and 1/200, while another seven combinations (18 cases, 2.7%) showed probabilities<1/200. Combinations with probabilities<1/200 were difficult to secure with routine inventory alone and required reliance on rare donor repositories or frozen red blood cell reserves. Conclusion Mixed antibodies in the Chinese population exhibit a complex spectrum with RhCE antibodies as the core component coexisting with multiple antibodies from other systems. Early referral to rare donor programs is recommended for patients with multiple alloantibodies. RhCE typing could be considered as an adjunct test when constructing rare blood type repositories.

Key words: Mixed antibodies, Irregular antibodies, Rare blood types, Compatible transfusion, Cross-matching difficulty