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M‐ficolin is expressed on monocytes and is a lectin binding to N ‐acetyl‐ d ‐glucosamine and mediates monocyte adhesion and phagocytosis of Escherichia coli
Author(s) -
Teh C.,
Le Y.,
Lee S. H.,
Lu J.
Publication year - 2000
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.2000.00099.x
Subject(s) - lectin , escherichia coli , monocyte , ficolin , phagocytosis , chemistry , adhesion , microbiology and biotechnology , glucosamine , biology , biochemistry , mannan binding lectin , immunology , gene , organic chemistry
Summary Ficolins are a group of multimeric proteins that contain collagen‐like and fibrinogen‐like (FBG) sequences. Three types of ficolins have been characterized: H‐, L‐ and M‐ficolins. Both H‐ and L‐ficolins have demonstrated lectin activities. In the present study, the FBG domain of M‐ficolin was expressed and shown to bind to N ‐acetyl‐ d ‐glucosamine. M‐ficolin mRNA was expressed in monocytes but not in the more differentiated macrophages and dendritic cells. By flow cytometry, surface biotinylation and immunoprecipitation, we showed that M‐ficolin was associated with the surface of promonocytic U937 cells. M‐ficolin transiently expressed in COS‐7 cells was also clearly detected on the cell surface by immunoprecipitation. By flow cytometry, M‐ficolin was detected on peripheral blood monocytes but not on lymphocytes or granulocytes. Immobilized rabbit anti‐M‐ficolin F(ab′) 2 mediated U937 cell adhesion, and the antibody also inhibited phagocytosis of Escherichia coli K‐12 by U937 cells. Therefore, M‐ficolin might act as a phagocytic receptor or adaptor on circulating monocytes for micro‐organism recognition and may potentially mediate monocyte adhesion.