The antigen used for immunization is C3c. Thus, the antibodies react both with C3c as well as with the C3c part of native C3 and C3b. There is no reaction with C3d and C3a. Please see reference 1 where the use in immunofixation is described. The antibody can also be used for immunohistochemistry (2).
1. Whicher JT, Higginson J, Riches PG, Radford S. Clinical applications of immunofixation: detection and quantitation of complement. J Clin Pathol 1980,33:791-5. 2. Sinclair RA, Burns J, Dunnill MS. Immunoperoxidase staining of formalin-fixed, paraffin-embedded, human renal biopsies with a comparison of the peroxidase anti-peroxidase (PAP) and indirect methods. J Clin Pathol 1981,34:859-65.