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Clinical application of a flow cytometric direct antiglobulin test |
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| Authors: | Jeong-Shi Lin Tsung-Chi Hao Jau-Yi Lyou Ying-Ju Chen Hsueng-Mei Liu Cheng-Hwai Tzeng Tzeon-Jye Chiou |
| Affiliation: | From the Division of Transfusion Medicine and the Division of Hematology/Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei;and the College of Medicine, National Yang-Ming University, Taipei, Taiwan. |
| Abstract: | BACKGROUND: The clinical application of flow cytometric direct antiglobulin test (FC-DAT) has rarely been evaluated for patients with various diseases including immune and nonimmune hemolytic anemia. STUDY DESIGN AND METHODS: Blood samples from 380 patients with a variety of diseases were studied using the tube direct DAT and FC-DAT. The results of tube DAT and FC-DAT were compared. The predictive values of DAT for hemolysis were evaluated. RESULTS: Of 57 patients with autoimmune hemolytic anemia (AIHA), 6 of the 17 with a negative tube DAT (immunoglobulin G IgG]) had a positive FC-DAT (IgG) and 23 of the 36 patients with a negative tube DAT (complement 3d C3d]) had a positive FC-DAT (C3d). In 57 patients with AIHA, the incidence of positive results of FC-DAT (IgG) and tube DAT (IgG) were similar (42 positive vs. 40 positive); but in 323 patients without AIHA, the incidence of positive FC-DATs (IgG) was higher than that of tube DAT (IgG; 47 positive vs. 9 positive). The higher incidence of positive FC-DAT (C3d) than that of tube DAT (C3d) was seen in patients with AIHA (42 positive vs. 21 positive) as well as in patients without AIHA (61 positive vs. 5 positive). Both DAT (IgG) and DAT (C3d) positive has highest positive predictive value for hemolysis, followed by DAT (IgG) alone positive and DAT (C3d) alone positive. CONCLUSIONS: FC-DAT is a complementary test for diagnosing AIHA. There is a synergistic effect of the red blood cell–bound IgG and complement in predicting hemolysis. |
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