Adhesion of piliated Escherichia coli strains to phagocytes: differences between bacteria with mannose-sensitive pili and those with mannose-resistant pili.

Escherichia coli with mannose-resistant (MR) pili, in contrast to those with mannose-sensitive (MS) pili, did not adhere to rat peritoneal macrophages and human polymorphonuclear granulocytes, as measured by use of radioactive bacteria and by the chemiluminescence response induced by the cell contact. With some MS-piliated E. coli strains, unpiliated bacteria, obtained by growth at a pilus-restrictive temperature, did show MS adherence to phagocytes, presumably by virtue of bacterial cell wall adhesins which, like MS pili, recognize alpha-mannose-containing structures of the phagocyte membrane. Possible roles of MR pili, MS pili, and MS cell wall adhesins in the unspecific cellular host defense are discussed.