Latex agglutination assay for human anti-Brucella IgM antibodies.

We report here the development of a homogeneous, easy, precise and rapid anti-Brucella IgM antibody (Ab) latex agglutination assay based on particle counting. The interference of IgG Ab was eliminated by the addition of anti-gamma Fc and free Bru-LPS. Anti-mu Fc mAb enhanced the agglutinating activity of IgM antibodies and improved the sensitivity of the test. The possible interference of rheumatoid factor was eliminated by adding human aggregated IgG. The assay is complete in 45 min, with an interassay variation of 9%. The assay correlates well (r = 0.94) with the accurate but time consuming capture ELISA.