When antibodies are floating, they do not trigger any immune reaction. However, when an antigen is bound to the antibody, then the resulting complex activates immune reactions.
How exactly these complexes trigger immune reactions? I think it is via their Fc fragment but what is the difference between a free antibody and an antibody with antigen bounded, so that the one does not trigger immune responses while the other does?
Also, how strong is the Ab/Ag bond? does it break after few seconds?