IMMUNE ELECTRON-MICROSCOPY OF CROSS-REACTIONS BETWEEN MYCOPLASMA-PNEUMONIAE AND HUMAN-ERYTHROCYTES

Respiratory infection with M. pneumoniae evokes immunoglobulin M autoantibody which agglutinates human erythrocytes at 4.degree. C (cold agglutinin) and is specific for [blood group] I antigen [Ag]. Cross-reactions between surface Ag of M. pneumoniae and human erythrocytes, previously examined by serological analysis, were examined by transmission and scanning electron microscopy. Ferritin-labeled human anti-mycoplasmal and rabbit antisera to erythrocyte membrane components reacted with Ag on the surface of M. pneumoniae was blocked by the same antisera without ferritin label. The cross-reactive specificity may lie in peripheral areas of the mycoplasmal cell, probably in a surface carbohydrate which has antigenic identity with erythrocyte glycoprotein.