However, antibodies produced by infection or antigens have multiple epitopes or antigenic determinants, each of which generates separate clones of lymphocytes.
This results in anti sera containing immunoglobulins of different classes with specification against different epitopes of the antigen.
On the other hand, when a clone of lymphocytes or plasma cells undergoes selective proliferation, as in multiple myeloma, antibodies with a single antigenic specificity accumulate. Such antibodies produced by a single clone and directed against a single antigenic determinant are called monoclonal antibodies.
Kohlrabi and Milstein in 1975, developed an ingenious method for the large scale production of monoclonal antibodies against any desired antigen. In 1984 the Nobel Prize for medicine was awarded to them, for the development of hybridoma technology.
Hybridomas are somatic cell hybrids produced by fusing antibody forming spleen cells with myeloma cells. The resultant hybrid retains the antibody producing capacity of the spleen cell and the ability of the myeloma cells to multiply indefinitely.
Human monoclonal antibodies have subsequently been developed. Genes for particular antibody fragments have been fused to bacteriophage genes. Whole libraries of such antibodies have been built using bacteriophages. Large quantities of the desired antibody can be prepared by infecting bacteria with the appropriate bacteriophage. Such antibody engineering holds great promise for immunotherapy.
Text Book Of Microbiology