An enzyme-linked antiglobulin test (ELAT) using low ionic strength saline for the initial red cell sensitisation phase, and alkaline phosphatase conjugated antiglobulin (AP-AHG), has been compared with a conventional low ionic strength antiglobulin test in testing 222 red cell antibodies of various specificities. A wide variation in absorbance values was observed at all levels of haemagglutination strength. Relatively higher absorbance values were obtained with anti-K compared with the agglutination gradings. Haemolysis was eliminated by modifying the substrate buffer used for diluting the AP-AHG, since fixation of red cells prior to sensitisation significantly reduced the sensitivity of the ELAT. Five commercial AP-AHG reagents compared in tests with D, Fy^a, K and Jk^a antibodies varied markedly in performance, some being unsatisfactory. The ELAT can be effectively used for antibody detection as well as quantitative determinations but requires automation to realise its full potential.

A 25-year-old man with rapidly progressive glomerulonephritis developed an autoantibody with anti-M specificity following haemodialysis and renal transplantation. The patient’s red cells typed as MN. The antibody was an IgM globulin which displayed marked dosage effect and variable pH dependence. The thermal range of reactivity extended to 37 ° C. The stimulus for the production of the antibody is uncertain.