Mannose binding protein (MBP) enhances mononuclear phagocyte function via a receptor that contains the 126,000 M(r) component of the C1q receptor.
Mannose-binding protein (MBP), C1q, the recognition component of the classical complement pathway, and pulmonary surfactant protein A (SP-A) are members of a family of molecules containing a collagen-like sequence contiguous with a noncollagen-like sequence, and usually having the properties of a lectin. C1q and SP-A have been shown to enhance monocyte FcR- and CR1-mediated phagocytosis, suggesting that the common structural features of the collagen-like domains may provide a basis for this immunologically important function. Results presented here demonstrate that MBP also enhanced FcR-mediated phagocytosis by both monocytes and macrophages, and stimulated CR1-mediated phagocytosis in human culture-derived macrophages and in phorbol ester-activated monocytes. Furthermore, a monoclonal antibody that recognizes a 126,000 M(r) cell surface protein and inhibits C1q-enhanced phagocytosis, inhibited the MBP-mediated enhancement of phagocytosis. Thus, the receptors that mediate the enhancement of phagocytosis by MBP and C1q share at least one critical functional component, the 126,000 M(r) ClqRP.
Tenner
A J
AJ
Department of Molecular Biology and Biochemistry, Irvine 92717, USA.
Robinson
S L
SL
Ezekowitz
R A
RA
D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D015922:Complement C1q / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D037241:Mannose-Binding Lectins; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D010587:Phagocytosis; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction
D002352:Carrier Proteins; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D015922:Complement C1q