Abstract: Objective The specificity of HLA and HPA antibodies as well as C1q-HLA antibodies in patients with platelet transfusion refractoriness （PTR） was analyzed to determine the clinical significance of C1q-HLA antibody for PTR patients. Methods LABScreen® Single Antigen （LSA） kit and C1qScreen™ kit were used to detect the specimens from HLA antibody-positive PTR patient to analyze the specificity of HLA and HPA antibodies, and whether these HLA antibodies could combine with complement component C1q （i.e. C1q-HLA antibodies）. Results In 40 patients, 10 patients （25%） had HPA antibodies which were mainly against glycoprotein GP IIb/IIIa. In 39 cases of HLA-LSA-Positive and 28 C1q-positive patients, the percentage of panel reactive antibody （PRA%） and Max mean fluorescence intensity （MFI） of LSA-positive patients were significantly higher than those of C1q-HLA-positive patients. There was no significant difference in the CCI value between C1q-HLA-positive and -negative patients after random platelet transfusion. Different status of HLA antibodies had no significant effect on finding compatible cross-matched platelets for PTR patients. Conclusion The results of this study showed that there was no direct correlation between C1q-HLA antibodies and clinical result of platelet transfusion. The occurrence of C1q-HLA antibodies may not increase the difficulty of finding compatible cross-matched platelets for PTR patients.

Key words: Platelet transfusion refractoriness, HLA antibodies, HPA antibodies, C1q-HLA antibodies