Combining Regions of Antibodies

When a mammalian organism is immunized with an antigenic determinant, a highly complex humoral immune response is induced. This consists of a large number of antibodies complementary to the antigenic determinant. Such antibodies may vary in class and subclass. Furthermore, within a single subclass, there are differences in the energy of interaction with which each antibody of the population binds the antigenic determinant. These interactions may be viewed at a single point in time, although the antibodies expressed at any one time in the immune response may be only a fraction of the number that the animal is capable of producing. Certainly, in viewing these antibodies over a period of time, there are shifts in the populations produced after the initial immunization.