title: Clinical application of a flow cytometric direct antiglobulin test.
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.
  
  
  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.
authors.affiliation: Division of Transfusion Medicine, Department of Medicine, Taipei Veterans General Hospital, No. 201 Section 2 Shih-Pai Road, Taipei, Taiwan. jslin@vghtpe.gov.tw
authors.forename: Jeong-Shi
authors.initials: JS
authors.lastname: Lin
authors.forename: Tsung-Chi
authors.initials: TC
authors.lastname: Hao
authors.forename: Jau-Yi
authors.initials: JY
authors.lastname: Lyou
authors.forename: Ying-Ju
authors.initials: YJ
authors.lastname: Chen
authors.forename: Hsueng-Mei
authors.initials: HM
authors.lastname: Liu
authors.forename: Cheng-Hwai
authors.initials: CH
authors.lastname: Tzeng
authors.forename: Tzeon-Jye
authors.initials: TJ
authors.lastname: Chiou