ADHERENCE OF MYCOPLASMA-PNEUMONIAE TO HUMAN ALVEOLAR MACROPHAGES

The human pathogen Mycoplasma pneumoniae causes primary atypical-cold agglutinin-positive pneumonia. Since alveolar macrophages internalize mycoplasma as part of their immune defense, we studied characteristics of the human macrophage receptor for opsonized and nonopsonized M. pn eumoniae. The glass-adhering subpopulation of M. pneumoniae attached m ore than the non-adherent subpopulation. The attachment was dose-depen dent and enhanced by opsonization in the presence of human serum. It i s inhibited by sulfated compounds such as dextran-sulfate and polyanet holsulfonic acid, but not by dextran or several monosaccharides, sugge sting that sulfated glycolipids on the macrophage surface may act as r eceptors for M. pneumoniae binding. In addition, sialylated compounds, such as fetuin and alpha 1-acid glycoprotein, were found to be potent inhibitors of the attachment, also indicating the role of sialic acid residue in recognition and attachment of M. pneumoniae to human alveo lar macrophages.