The class of antibodies sensitizing bacteria measured by mixed reverse passive antiglobulin haemagglutination (MRPAH).

A test is described which is capable of differentiating and measuring by titration the individual classes of antibody reacting with a bacterial suspension. The serum or fluid under test is incubated with the bacteria which are then very well washed and added to indicator red cells linked with specific antiglobulin reagents. Sensitization of the bacteria by a particular class of antibody is shown by haemagglutination (passive) of the appropriate red cells. Agglutination of the bacteria themselves does not preclude an analysis. The reaction, which has been developed on a brucella system, has been designated Mixed Reverse Passive Antiglobulin Haemagglutination (or MRPAH for short).