An antibody is a glycosylated protein complex that is synthesized and secreted by immune B cells
Its formation is usually in response to the exposure of the immune system to a foreign or non-self molecule, such as an infectious agent, or transplanted tissue.
An antibody contains four polypeptide proteins chains: two heavy chains and two light chains.
The chains have variable domains, which bind the target antigen and constant domains, which mediate events downstream of antigen binding.
Such events include complement, fixation, and antibody dependent cellular toxicity.
The ability of the immune system to generate a glycoprotein capable of recognizing foreign proteins, while ignoring self antigens, is not fully understood.
Monoclonal antibodies, have a defined specificity, binding to specific epitropes on a specific antigen, and is derived from a single, immortalized B cell clone.
Bifunctional antibodies are anybody molecules in which one arm targets a tumor antigen, and another arm targets a T cell surface molecule such as CD3.