Abstract: Objective To analyze the distribution characteristics of HLA-I loci (A, B) in apheresis platelet donors in Shijiazhuan area, explore the probability of finding an HLA-matched platelet donor in platelet donor pools in Shijiazhuang area, and evaluate the minimum pool size of platelet donor gene database. Methods HLA-I loci A and B genotypes of 1 935 unrelated platelet donors in Shijiazhuang area were performed by polymerase chain reaction(PCR) using sequence-specific primers (PCR-SSP) and sequence-based typing (PCR-SBT) methods. HLA genotype obtained were converted to antigenic specificity, calculated genetype frequency and haplotype frequency, and evaluated the minimum pool size of platelet donor gene database. The cross-reactive group (CREG) phenotype frequency and its mismatch rate were counted. Results A total of 19 HLA-A locus phenotype specificities were identified in 1 935 unrelated platelet donors, and the highest frequency antigens are A2 (0.313 4) and A11 (0.158 4). A total of 43 B-locus phenotype specificities were identified, and the highest frequency antigens are B13 (0.118 1) and B61 (0.086 3). 355 HLA-A-B haplotypes were observed, of which 28 frequencies were greater than 0.01, the highest frequencies haplotypes were A2-B13 (0.044 4) and A2-B62 (0.029 5). 1C-2C and 7C-5C have the highest mismatch rate of CREG epitopes of A-A and A-B antigens, and 4C-6C has the highest mismatch rate of Broad CREG in apheresis platelet donors in Shijiazhuang area. Conclusion In theory, 93.18% of patients have a 95% ;probability to find at least one HLA-matched donor in a platelet donor pool with a total storage capacity of 1,500 patients. The platelet donor pool size of 1935 would basically meet the needs of patients with platelet transfusion refractoriness in Shijiazhuang area.

Key words: Platelets, HLA-I gene, Gene frequency, Haplotype, CREG