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