Modification of glycosylation by tunicamycin treatment inhibits lectin-mediated adhesion of Streptococcus pneumoniae to various tissues.

Oligosaccharide moieties of cell surface glycoconjugates are thought to be involved in recognition events associated with infectious diseases. Treatment of Streptococcus pneumoniae (which exhibits well defined surface lectins) with subinhibitory concentrations of the antibiotic tunicamycin was found to block the protein glycosylation of the bacterial surfaces. Since bacterial lectins (adhesins) are in most cases glycoproteins and play an important role in the organ specificity of infectious diseases, adhesion of Streptococcus pneumoniae to frozen sections of lung, meninges and kidney (from Balb/c-mice) was almost totally lacking after inhibition of the biosynthesis of N-linked carbohydrate chains which are important for an adequate lectin function. Chemiluminescence measurements of human granulocyte stimulation yielded results suggesting a great importance of lectin-carbohydrate interactions in this process, too. These experimental data indicate that the presence of specific cell surface carbohydrates is required for a successful completion of the adhesion phase of pathogenic bacteria in infectious diseases and for the induction of granulocyte stimulation.