Invitrogen™ Complement C3b Monoclonal Antibody (755)

Inactive complement component 3b (iC3b) is a 42kDa neoantigen present in blood serum. Cleavage of C3b into iC3b by the protease factor I, in the presence of cofactors, changes the structure and resulting binding properties, preventing binding by complement factor B and properdin. This prevents further progression of the complement pathway, providing another mechanism by which the complement pathway may be regulated. iC3b is thought to play a role in inducing tolerance, binding complement receptor type 3 on antigen presenting cells and stimulating them to produce transforming growth factor beta2 and interleukin-10. It is thought to stimulate B-cells via the CD21 receptor providing a link between the innate and adaptive immune responses. Additionally iC3b acts as an opsonin which is recognised by complement receptor 3 expressed on leukocytes or complement receptor of the immunoglobulin superfamily (CRIg) on Kupffer cells, stimulating phagocytosis of the tagged cells. iC3b levels are often elevated in diseases such as Systemic Lupus Erythematosis and Rheumatoid arthritis.