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- Title
Identification of the serum factor required for liposome-primed activation of mouse peritoneal macrophages. Modified α<sub>2</sub>-macroglobulin enhances Fcγ receptor-mediated phagocytosis of opsonized sheep red blood cells.
- Authors
Murai, M.; Aramaki, Y.; Tsuchiya, S.
- Abstract
Culture supernatant, prepared by incubating fetal calf serum and liposome-treated B cells, augments mouse peritoneal macrophage Fcγ receptor-mediated phagocytosis of IgG-opsonized sheep red blood cells. The activation process was hypothesized to be as follows. B-cell membranous glycosidases stimulated by liposomes. convert serum factor to a macrophage-stimulating active serum factor. As the active serum factor loses its activation potential by the addition of mannose or by digestion with α-mannosidase, mannose residues at the terminal present in the active serum factor are hypothesized to contribute to macrophage activation. The active serum factor was purified on a concanavalin A-Sepharose 4B column, and identified as a modified form of α2-macroglobulin by immunochemical analysises. On non-denaturing polyacrylamide gel electrophoresis, modified α2-macroglobulin showed a slow form, while α2-macroglobulin-trypsin and α2-macroglobulin-methylamine complexes, which bind specifically to α2-macroglobulin receptors, showed a fast form and did not activate macrophages. These findings demonstrate that α2-macroglobulin is the essential serum factor in liposome-primed macrophage activation, and that modified α2-macroglobulin with mannose residues at the terminal sugar chain binds to macrophage mannose receptors, but not α2-macroglobulin receptors, and increases Fcγ receptor-mediated phagocytosis of IgG-opsonized sheep red blood cells.
- Subjects
LIPOSOMES; MACROPHAGE activation; MACROPHAGES; MACROGLOBULINS; PHAGOCYTOSIS; IMMUNE response; IMMUNOLOGY; MEDICAL sciences
- Publication
Immunology, 1995, Vol 86, Issue 1, p64
- ISSN
0019-2805
- Publication type
Article