An antibody is a glycoprotein molecule produced by plasma cells (white blood cells). In the immune system, antibodies recognize and bind to specific antigens, such as bacteria or viruses, and aid in their destruction. The immune system's immune response to antibodies is extremely specific and complex. As a result, antibodies are complex glycoproteins. Any immunochemical technique works on the premise that a certain antibody will combine with an exclusive antigen to form an antibody-antigen complex.