Activation of B cells by antigen leads to production of antibody specific for those antigens.
Subsequently, the antibody produced binds to the antigen and reduces the concentration of that specific antigen. Eventually, antigens are completely removed and no further stimulation of the production of antibodies to that particular antigen occurs. As long as free antigens are present, stimulation to B cells continues to produce the antibodies.
Cross linking of receptors: Antibodies released in response to antigenic stimulation binds to their specific antigens and reduce the chances of antigen binding and further induction of antibody production without affecting immunological response to other antigens. This suppresses antibody production for that specific antigen.
An antigen that is complexes with antibody has differential effects on immune responses. At low Ab/ Ag ratios, suppression of antibody production can occur.
Under these conditions, immune complexes can bind to both membranes bound Ig and FcRs of the B cells.
This suppresses antibody production. In contrast, at high Ab/Ag ratios, immune responses can be stimulated. This occurs through binding to FcRs on APCs that leads to activation of T helper cells and subsequent enhancement of immune responses.
Idiotypic net works:
The antibodies produced (Ab -1) not only react with the antigen, but also serve as antigens for the immune system. This triggers the production of a second level of antibodies (Ab-2).
The second level antibodies react with Ab-1 and induce production of antibodies (Ab -3). The process continues for several generations. The antibodies formed against the Ab formed by the immune system it self s are known as idiotype antibodies.
At each step, the concentration of antibodies available to provoke formation of idiotype antibodies is less than in the preceding step. As a result, a level is eventually reached at which there is insufficient antibodies to provide and antigenic signal.