The immunoelectroosmophoresis (IEOP) test was compared with gel diffusion and complement fixation (CF) tests for sensitivity in detecting hepatitis-associated antigen (HAA) in the sera of hepatitis patients, for titration of HAA, and for detection of antibody to HAA. The IEOP test was found to be slightly more sensitive than either gel diffusion or CF tests for detection of antigen in the patients' sera. Titers of HAA demonstrated by IEOP were higher than those seen in gel diffusion tests but lower than CF titers. The gel diffusion test with an "enhancement" pattern was found to be more reliable than the other two procedures for detection of low levels of anti-HAA, due to the greater inhibitory effect of an antigen excess in the IEOP system and the possible masking of low levels of antibody by anticomplementary activity in the CF test system. Staining of immunoprecipitates in the IEOP test contributed little to the sensitivity of the test for detection of HAA.
The complement system can be activated by antigen-associated antibody. In the classical pathway of complement activation, C1q, C4b, and C3b are all able to bind to the Fc portion of IgG or IgM. Find the latest research on antibodies and complement activation here.