Biomedical subjects
Publications and source records attributed to C Kantor.
Cellular adhesion is of fundamental importance in leukocyte physiology. It is a complex, strictly regulated process, which involves the participation of several cell surface glycoproteins. Among the most important are the Leu-CAMs or the CD11/CD18 integrin receptors, and their adhesion ligands ICAM-1 (CD54) and ICAM-2. In this review we summarize some recent work on various aspects of these molecules.
The leukocyte adhesion 90-kDa glycoprotein GP90 (antigen CD18) is non-covalently associated separately with cell-surface glycoproteins GP160 (antigens CD11a, TA-1, LFA-1), GP155 (antigens CD11b, OKM1, MO1) or GP130 (antigens CD 11c, Leu-M5). Large amounts of these protein complexes were purified to homogeneity from blood mononuclear leukocytes by immunoaffinity chromatography using a monoclonal antibody. GP90 was further isolated by preparative gel electrophoresis in the presence of sodium dodecyl sulfate. Rabbit antiserum towards the complex inhibited phorbol-ester-induced adhesion of leukocytes. The antiserum towards purified GP90 reacted more strongly with the denatured GP90 protein, but showed reactivity also with GP160 protein, indicating structural homologies between GP90 and GP160. The amino acid composition of GP90 was determined. Its N-terminus was found to be blocked. Treatment of GP90 with endo-beta-N-acetylglucosaminidase F, but not with endo-beta-N-acetylglucosaminidase H, reduced the apparent molecular mass to 75 kDa, indicating the presence of five or six N-linked complex-type oligosaccharides/molecule.
The leucocyte surface glycoproteins CD11a (gp160, LFA-1 antigen, TA-1 antigen), CD11b (gp155, Mac-1 antigen, OKM1 antigen, Mo-1 antigen), CD11c (gp130, Leu-M5 antigen), and CD18 (gp90) constitute three heterodimers with different alpha chains and a common beta chain. Monoclonal antibodies to CD11a, b, or c block adhesion of certain types of leucocytes only, while several antibodies to CD18 inhibit adhesion in all of them. The functionally important site or sites on CD18 are not known. We have now isolated the CD11a,b,c-CD18 leucocyte antigen complex in large amounts from human leucocytes, and produced several new monoclonal antibodies reacting with CD18. One of these antibodies, like those described earlier, inhibits leucocyte adhesion, whereas the others do not. By means of competition experiments, at least four epitope regions were found. These antibodies should be valuable in elucidating the regions essential in CD18-mediated leucocyte functions.
Monoclonal antibody LB-2 to a surface antigen on human B cells, lymphoblast, monocytes and vascular endothelial cells largely inhibited adhesion among Epstein Barr virus-immortalized normal B cells (EBV-B) and concanavalin A-stimulated blood mononuclear cells (Con A-BMC) before and after phorbol ester treatment. The antibody inhibited to a lesser extent phorbol ester-induced aggregation of monocytes, U937 cells and fresh BMC and had virtually no inhibitory effect on the adhesion among enriched T cells and granulocytes. A surface glycoprotein band of 84 kDa was obtained from EBV-B cells by immunoprecipitation and gel electrophoresis. Immunological and biochemical studies clearly distinguished this molecule from gp90 and associated glycoproteins which also mediate leukocyte adhesion.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.