Phagocyte recognition by lectin receptors

A "lectin-like" receptor for bacterial cell wall sugars, originally described in the membrane of mouse peritoneal macrophages, which facilitates binding of various bacteria to the macrophage surface, has now been shown to be present on most phagocytes from a variety of species. The role of such a receptor in the inflammatory response has been investigated by examining changes in its expression in response to chemoattractants. The chemoattractants, whilst enhancing or not altering expression of C3 and Fc receptors, respectively, appeared to decrease lectin receptor expression. The possibility of a relationship between I-region gene products of the major histocompatibility complex (MHC) and the bacterial binding lectin receptor was investigated. It was found that various conventional and monoclonal antibodies directed against I-region determinants inhibited binding of bacteria to mouse peritoneal macrophages. These findings suggest the need to examine the possibility that, in addition to phagocytosis and elimination of bacteria, the lectin receptor may also be involved in antigen presentation and macrophage-T-lymphocyte cooperative events leading to an immune response.