2 drops of serum are incubated at 37°C for 15 minutes with 1 drop of 3 - 5% cells and 2 drops of enzyme. The test is centrifuged (to enhance the reaction and form a cell button, because of the short 15 minute incubation), and read macroscopically only for agglutination and hemolysis. Note: the test is not read microscopically, because enzymes enhance some cold IgM antibodies like autoanti-I, which are clinically insignificant.
The one-stage test is not as sensitive as the two-stage test. Also, if the test incubates too long, the enzyme can break antibodies up into 2Fab and 1Fc fragment, thus destroying their ability to agglutinate cells.
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| One-Stage Test |