C3b/iC3b/C3c

The complement system is an important part of the humoral response in innate immunity, consisting of three different pathways. The third complement component, C3, is central to the classical, alternative and lectin pathways of complement activation. Activation products of the complement cascade contain neo-epitopes that are not present in the individual native components. Proteolysis by certain enzymes results in the cleavage of C3 into C3a and C3b. C3b becomes attached to immune complexes and is further cleaved into iC3b, C3c, C3dg and C3f. The monoclonal antibody 2/11 is specific for cleaved C3 fragments C3b, iC3b, and C3c, and for activated C3. Therefore, positive reactivity in tissues is associated with activation of he complement cascade and C3 cleavage.