In Regulation of Gene Expression 3. A Variety of Mechanisms in Eukaryotes, a brief reference was made to antibodies or immunoglobulins, while discussing the regulation of the expression of their corresponding genes. The role of rearrangement of DNA sequences in generating antibody diversity was discussed there in some detail. The subject of production and uses of antibodies has become a very important area of research in recent years. However, for purposes of research and -their use in medicine, antibodies are isolated by sacrificing animals, after hyperimmunizing them with antigens. From such hyperimmunized animals, the blood serum may be taken and antibodies may be isolated from the serum.

A sample of antibodies, whenever separated from serum after induction due to an antigen is usually heterogeneous, because the cells keep on producing a variety of antibodies. Consequently, the antibody preparation made from serum above will not have the desired specificity and therefore can not be utilized for diagnosis or screening. Monoclonal antibodies (Mab), on the other hand, are homogeneous immunological reagents of defined specificity, so that these can be utilized for diagnosis and screening with ease and certainty. The discovery, production, genetic manipulation and uses of these monoclonal antibodies will be described in this section.