Horse erythrocyte glycoprotein-latex reagent that reacts with infectious mononucleosis heterophile antibody.

A sialoglycoprotein from horse erythrocytes was isolated in essentially homogeneous form and found to contain the neuraminidase-sensitive determinant of the horse erythrocyte for Paul-Bunnell heterophile antibodies of infectious mononucleosis. This reactivity was retained after covalent coupling of the antigen to latex particles. The latex reagent has greater stability (greater than 3 years) than either fresh or preserved horse erythrocytes. It can be used in a direct slide test; no absorption of the serum is necessary. The new test compared favorably with some standard tests for infectious mononucleosis antibody which use horse erythrocytes. Agreement of the latex test with the absorbed fresh horse cell test was 100%, and agreement with a stabilized horse erythrocyte spot test was 94%. The latex test also agreed 100% with a radioimmunoassay for the detection of heterophile antibody with 125I-labeled horse erythrocyte glycoprotein. The new latex test was compared with a bovine erythrocyte glycoprotein-latex test, and a correlation of 94% was observed. In addition, it was compared with the Wöllner test (enzyme-treated sheep cell-absorbed sheep cell agglutination test) with which it agreed in 92% of samples tested.