Immunological cross-reactivity between a glycoprotein isolated from Trichophyton mentagrophytes and human isoantigen A.

A glycoprotein isolated from the cell wall of Trichophyton mentagrophytes was assessed for its cross-reaction with human blood group isoantigens. Rabbit antiglycoprotein antibodies agglutinated human erythrocytes of blood groups A1 and A2, and precipitated Blood Group Substance A in agarose gels. Erythrocytes of blood group B were only slightly agglutinated, and O(Rho+) and O(Rho-) erythrocytes were not. Additionally, the glycoprotein was shown to specifically inhibit isoagglutination of erythrocytes of group A. Partial identity between the glycoprotein and a crude extract of the fungus was demonstrated by immunodiffusion. Analyses revealed the glycoprotein to be composed of approximately 17% protein and 80% carbohydrate. The glycoprotein was found by indirect immunofluorescence to be located in the mycelial cell wall. The possibility that cross-reacting antigens may lead to a chronic, spreading infection is discussed.