iC3bfragmenttien
iC3b fragments are proteolytic products of C3b that arise during the regulation of the complement system. They form when C3b bound to a surface is cleaved by the serine protease factor I in the presence of cofactors that include factor H, CR1 (CD35), MCP (CD46), or C4b-binding protein. The resulting iC3b remains covalently attached to the surface and retains opsonizing activity while losing the ability to participate in further amplification of the cascade.
Historically, C3b functions as a key amplification fragment of complement. After C3b is deposited on a target,
Receptors and function: iC3b is recognized by phagocyte receptors such as CR3 (CD11b/CD18) and CR4 (CD11c/CD18),
Clinical and research relevance: The presence and pattern of iC3b deposition reflect local complement activity and