Improvement of enzyme-linked antiglobulin test by using an antiglobulin linked to glucose oxidase: description of the technique

The classic enzyme-linked antiglobulin test (ELAT) used to detect and quantify the amount of IgG antibodies on red blood cells (RBC) is sensitive to hemolysis and erythrocyte enzymatic activities. We describe a new ELAT by using glucose oxidase (GO) linked to antihuman IgG. The optical density baseline of GO-ELAT, alkaline phosphatase-ELAT and peroxidase-ELAT were, respectively, 0.180, 0.350 and 0.550. This very low baseline of GO-ELAT was due to the absence of hemolysis (the pH of the GO substrate is 6.5). This technique is ten times more sensitive than the indirect antiglobulin test and detects up to 1 ng/ml of anti-D alloantibodies. Additional advantages of the technique are (1) there is no intrinsic GO enzyme in RBC, and (2) it is not necessary to fix the RBC.