Role of Gel test in Hereditary Anemia's to Detect Alloimmunization and Autoimmunization
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Traditionally, red cell antibody screening and identification are done by agglutination methods in the tube. The gel test is an innovative approach to blood group serology. This technology addresses the issue of standardization and incorporates sensitivity, specificity, and efficiency. The gel micro typing system utilizes a sephadex gel to capture agglutinates in a semi-solid medium. This enhances visualization of agglutination as compared to the traditional tube techniques. In the latter, the agglutinate, particularly in weak reactions, mixes with the free cells at the bottom of the tube, making visualization difficult. The capacity of the gel test to separate RBCs from their surrounding fluid permits an antiglobulin test to be performed without washing. At the beginning of centrifugation, the RBCs are pulled away from the suspension medium (unbound serum globulin) and enter the gel first. The surrounding medium remains above the gel and the characteristics of the gel prevent the medium from interfering with the antiglobulin reaction. Sensitized RBCs agglutinate as they were expose to the antiglobulin reagent in the gel and are trapped. Unsensitized RBCs are not agglutinated and pass through the gel to pellet at the bottom of the microtube. Allogeneic blood transfusion is a form of temporary transplantation. Procedure introduces a multitude of foreign antigens and living cells into the recipient that will persist for a variable time. Approximately 0.1–2% of patients who receive transfusions develops anti-RBC antibodies. In patients who are transfused regularly (e.g. patients with sickle cell disease and thalassemia), the frequency of alloimmunization is much higher, affecting 10–38%. A hemolytic transfusion reaction occurs following transfusion of an incompatible blood component.
This study has been undertaken on the multiple transfused recipients of thalassemia and sickle cell anemia in the Blood Bank, N.S.C.B. Medical College, Jabalpur (Madhya Pradesh), for detection of alloantibodies and autoantibodies using gel test as methodology. The study constitutes clinically diagnosed patients of thalassemia and sickle cell anemia. The alloantibodies detected were 08/30 (26.7 percent) and autoantibodies 01/30 (3.3percent) by gel test, auto control was performed for all indirect antiglobulin test (IAT) and direct antiglobulin test (DAT) positive samples. All alloantibodies found to be of Rh and Duffy blood group systems.
Alloimmunization, Sickle cell disease, Thalassemia, Transfusion reaction, Indirect antiglobulin test.