Enzyme-linked antiglobulin test: an accurate and simple method to quantify red cell antibodies.

An enzyme-linked antiglobulin test was used to quantify the amount of IgG antibodies on red blood cells. Erythrocytes were sensitized with various blood group antibodies, washed, incubated with antiglobulin conjugated with alkaline phosphatase, washed, substrate was added and the optical density of the product was measured. This optical density was linearly proportional to the concentration of red blood cell antibodies incubated with the cells. The assay was easy to perform, had a standard deviation of 7 per cent on replicated assays, and was more sensitive than the manual antiglobulin test.