For the detection of antigen in serum samples, I think dissociation of immune complexes formed in-vitro or in-vivo is necessary so that bound antigens can be detected. Can you please enlighten me with the protocols you use along with references?
you can use ELISA to detect antigen, it doesnt matter if is in complex with antibodys in the sample because you put in the ELISA more concentration of your antibody so they compete for the antigen and if you put more concentration at the end they take out natural antibody just for competition....other way to detect antigen in serum could be by inmunoelectrophoresi...in this case you are trying to form a complex antibody-antigen by diffusion so you need quantify how much serum needs for your sample, distance you have to put it and more dates that are not standarizated...but is so usefull...if you do it, think that link between antigen-antibody will be form by an equivalence relation...so at the end you have some marks in your gel that reveal the union...but is semiqualitative because if the relation between antiserum and antigen is not good....you wont see anything...
try to see this one, i hope it will be usefull !!
Engvall, E., and P. Perlmann. 1971. Immunochemistry 8: 871.
There is a simple way: Immune complexes are broken at low pH. So you can start your incubation in the ELISA plate under acetic conditions (pH 2.0, 0,001 mol/L Gylcine/HCl-buffer) and now switch after 15 min to neutral pH by adding PBS. This will start the immune reaction, now with both - the autoantibody from the former immune complex and the antibody at the solid phase.
You have a good chance to detect the real concentration if the antibody at the solid phase has the higher affinity (which is normally given). The law of mass action will do the rest. The antibody with the higher affinity will win the race for the antigen.