Binding of Gc globulin (vitamin D binding protein) to C5a or C5a des Arg is not necessary for co-chemotactic activity.
J Leukoc Biol
; 58(1): 55-8, 1995 Jul.
Article
em En
| MEDLINE
| ID: mdl-7616106
ABSTRACT
Gc globulin (vitamin D binding protein) has been shown to augment significantly the leukocyte chemotactic activity of the activated complement peptides C5a and C5a des Arg. However, the mechanism of chemotaxis enhancement is not known. Natural C5-derived peptides contain a carbohydrate side chain that comprises approximately 25% of the mass of the 11-kDa peptides. Previous studies have demonstrated that Gc globulin binds to C5-derived peptides via sialic acid residues on this carbohydrate side chain. The necessity of this carbohydrate side chain for chemotaxis enhancement by Gc globulin was investigated by using both natural (glycosylated) and recombinant (carbohydrate-free) peptides. The dose-response curves of neutrophil chemotaxis to recombinant C5a or C5a des Arg plus Gc globulin were identical to those observed with the naturally derived peptides, despite the fact that natural C5a bound to Gc globulin while the recombinant C5a failed to bind this protein. Moreover, neutrophils pretreated with Gc globulin then washed before addition to the chemotaxis assay displayed significantly enhanced movement to C5a alone. These results indicate that the binding of C5a/C5a des Arg to Gc globulin is not necessary for their chemotactic activity to be augmented. Furthermore, these results demonstrate that the co-chemotactic activity of Gc globulin is generated on the cell surface, independent of C5a binding to its receptor.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteína de Ligação a Vitamina D
/
Complemento C5a
/
Complemento C5a des-Arginina
/
Quimiotaxia de Leucócito
/
Neutrófilos
Limite:
Humans
Idioma:
En
Revista:
J Leukoc Biol
Ano de publicação:
1995
Tipo de documento:
Article