Fibronectin binds to C1q: possible mechanisms for their co-precipitation in cryoglobulins from patients with systemic lupus erythematosus.
Fibronectin and C1q frequently co-precipitated in cryoglobulins from patients with SLE. As a portion of the C1q molecule is similar to collagen to which fibronectin has a high affinity, we studied whether fibronectin specifically bound to C1q. Fibronectin was found to bind to both native and heat-inactivated C1q. The binding was enhanced by Ca++ and low ionic strength. We have also demonstrated that fibronectin is capable of binding to C1q fixed to immune complexes. The interaction between fibronectin and C1q may play a role in cryoglobulin formation and in clearance of immune complexes by reticuloendothelial system.
D000936:Antigen-Antibody Complex; D002118:Calcium / Q000494:pharmacology; D011232:Chemical Precipitation; D003166:Complement Activating Enzymes / Q000378:metabolism*; D015922:Complement C1q; D003450:Cryoglobulins / Q000032:analysis; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008274:Magnesium / Q000494:pharmacology; D009994:Osmolar Concentration; D011485:Protein Binding
D000936:Antigen-Antibody Complex; D003450:Cryoglobulins; D005353:Fibronectins; D007074:Immunoglobulin G; D015922:Complement C1q; D003166:Complement Activating Enzymes; D008274:Magnesium; D002118:Calcium