Application of gel technology in the serologic characterization of autoantibody in DAT-positive autoimmune diseases.

Gel tests are now available for the determination of immunoglobulin classes and subclasses and complement fractions coating RBCs. These tests simplified serologic characterization of autoantibodies in various autoimmune diseases. The aim of this study was to evaluate the use of gel cards in the serologic characterization of autoantibody with regard to the immunoglobulin classes, complement fractions, and IgG subclasses, and the influence of these characteristics on hemolysis. Gel cards were used to characterize the RBC-bound autoantibodies in 66 DAT-positive patients. Hematologic and biochemical parameters such as Hb, reticulocyte count, serum bilirubin, and serum LDH were obtained from the patient files. Of the 49 patients carrying IgG on their RBCs, 21 (42.8%) were suffering from connective tissue disorders and another 16 patients (32.7%) had autoimmune hemolytic anemia. A total of 19 of these 49 patients had evidence of hemolysis. Thirteen of the 17 patients (76.5%) whose RBCs were coated with more than one type of immunoglobulin and complement were experiencing hemolysis (p < 0.05). Seventy-five percent (21 of 28) of patients having IgG1, IgG3, or both on their RBCs showed hemolysis (p < 0.05). Thus, it is important to serologically characterize autoantibodies in autoimmune disorders to effectively predict the prognosis and disease outcome. This characterization can be performed effectively with the gel test, which can be introduced in blood centers as a replacement to the conventional tube technique.