The direct antiglobulin test (DAT) is used in investigating autoimmune hemolytic anemia, druginduced antibodies, hemolytic diseases of newborn and alloimmune reactions to recently transfused red cells. We performed 3,033 DATs in our blood bank
from
1985
to 1992. When using a polyspecific antihuman globulin reagent, the DAT was positive in 7.2% of all cases tested. In further studies using monospecific anti-IgG and anti-C3d reagents, three patterns of reactivity were founded: in 37% of cases, red
cells
are coated with IgG alone; in 18% of cases, the red cells are coated with both IgG and complement; and in 45% of cases only with complement.
We evaluated clinical significance of DAT positive results with the 227 patients' medical records which can be available for reviewing among the positive DAT patients. The male to female ratio of DAT positive patient was 1:2 and 41% of cases were
belong
to the 20-30 years old age group. The most common underlying disorders were systemic lupus erythematosus (29.5%), idiopathic (10.1%), hematologic malignancy (8.8%), and liver disease (6.2%).
Patients with warm reactive autoantibodies account for 60.4% of all DAT positive cases. Cold reactive autoantibodies were demonstrated in 11%, and the mixed-types were 2.6%. Drug-induced DAT positive findings were observed in 15.4% and the DAT
postitve
caused with transfusion associated alloantibodies were 7.5%. IgG warm-reactive autoagglutinins were more commonly detected in patients with autoimmune hemolytic anemia and drug induced hemolysis. Definite hemolysis was present in 37% of all DAT
positive
patients and especially in all patients with mixed type autoagglutinin. Drugs caused a positive DAT were cephalosporin, penicillin, isoniazid, and rifampicin.
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