Characterization of I/F1 glycoprotein as a receptor for Mycoplasma pneumoniae.

Serologic evidence of anti-I and anti-Fl cold agglutinins occurring in mycoplasma infections led to the isolation of I/Fl glycoprotein from human erythrocyte membranes. Mycoplasma pneumoniae bound to purified I/Fl glycoprotein in a dose-dependent fashion depending on sialylated carbohydrate determinants. This was shown by the decreased binding of mycoplasmas to either sialidase-treated I/Fl glycoprotein (dot blot analysis) or sialidase-treated erythrocytes (hemagglutination test). Structural properties of the receptor for optimal binding could be explored by hemagglutination inhibition assays. Glycophorins were excluded as receptors. These results indicate that Fl (and I) antigens are receptors for M. pneumoniae.