Structure and function of Mac-1 and its role in cancer immunotherapy / 中国癌症杂志

ABSTRACT

Mac-1,an adhesion molecule expressed on the surface of leukocytes,plays an important role in host-defence function and immunological response.It consists of two noncovalently linked polypeptides known as ?(CD11b) and ?(CD18) subunits.It contains two important domains known as I-domain which recognizes protein ligands and the lectin domain which recognizes polysaccharides.Mac-1 is expressed on nearly all neutrophils,monocytes,eosinophils and NK cells,but less on B cells,T cells and macrophages.Mac-1 functions as both an adhesion molecule for ICAM-1 expressed by stimulated endothelium mediating the diapedesis of leukocytes across the endothelium and a receptor for the iC3b fragment of complement responsible for cytotoxicity to microorganisms or target cells opsonized with iC3b.It can also form a complex with many membrane glycoproteins,functioning as a signal transducing partner for them.An important finding was that soluble ?-glucan could bind to Mac-1 and prime the receptor for cytotoxic function in response to iC3b-opsonized tumors,thus may pave the way for development of ?-glucan-like drugs that could generate Mac-1-dependent cytotoxicity following a humoral response to tumor antigens elicited by vaccines that would cause tumors to be opsonized with Abs and iC3b in cancer immunotherapy.