Abstract: Objective The positive rate of immune hemolytic reaction（IHTR）samples in Shanghai Blood Center has been increasing in recent years,gradually popularized with capillary technology,PEG enhancement technology and microcolumn agglutination card technology. These changes may affect the detection rate of IHTRs. Methods IHTR cases detected in the blood group reference laboratory of Shanghai Blood Center from March 2011 to March 2021 were reviewed. The inclusion criteria were the recent history of blood transfusion,the detection of Alloantibody and the detection or confirmation of the input of red blood cells reacting with the antibody. All included cases excluded newborns and patients with autoantibodies to prevent interference from maternal antibodies and mimicking antibodies. The antibody specificity and titer, patient diagnosis,hemoglobin,gender and age distribution,and the time from blood transfusion to detection of hemolytic reaction were caculated for all included cases. Results There were 100 IHTR samples. The diagnosis of patients was mostly tumor and MDS（myelodysplastic syndrome）; Among them,the hemolytic blood transfusion reaction caused by RH system antibody accounts for 78%,and the blood transfusion reaction caused by Kidd system accounts for 11%. Most of the antibody effects are low,and 80% of the titration is less than 4; The patient's DAT positive lasted for more than 8 weeks. Conclusion Hemolytic transfusion reaction can cause severe hemolysis in the recipient,which may seriously endanger the life safety of the patient. Most of the antibodies in IHTR samples are RH system antibodies. RhD,CcEe typing and the homotype transfusion can effectively reduce the occurrence of IHTR. The antibodies causing hemolysis are generally weak,and the incompatible transfused red blood cells are metabolized rapidly in vivo and are not easy to be detected,which makes IHTR easy to be ignored,resulting in repeated input of“matched”red blood cells and endangering the life of patients. In terms of detection technology,it is necessary to improve the detection sensitivity. The capillary technology is of great help to the detection of IHTR.

Key words: Transfusion reaction, Hemolysis, Alloantibody, Rh system