An enzyme-linked antiglobulin test to detect red cell globulins after glutaraldehyde fixation

The purpose of this study was to develop an enzyme-linked antiglobulin test (ELAT) for IgG on RBC without the hemolysis caused by the high pH of the alkaline phosphatase reaction. This was achieved by fixing the RBC with 0.05% glutaraldehyde after attachment of the antibodies. Assays using anti-D reference standards demonstrated the sensitivity to be 1-2 ng of antibody as compared to 7.5 ng for the manual indirect antiglobulin test. The coefficients of variation of these assays ranged from 10.4 to 20.1%. The mean background absorbance at 405 nm of 105 normal RBC samples was 0.08 +/- 0.03 SD. There was an increase in sensitivity of the test after the fixed RBC were stored. Dilute glutaraldehyde stabilizes the RBC membrane and the antigen-antibody linkage resulting in a more sensitive ELAT.