BIOTECHNOLOGY - V. H. Herasymenko - 2006

Part II. Special Biotechnologies

Chapter 14. BIOTECHNOLOGY FOR THE PRODUCTION OF MONOCLONAL ANTIBODIES (SINGLE-EPITOPE ANTIBODIES)

14.1. TRADITIONAL METHOD FOR OBTAINING ANTIBODIES

Traditionally, antibodies are obtained by administering an antigen to animals (rabbits, goats, sheep). In response to foreign antigens in the bloodstream, the animal's immune system activates the proliferation of B lymphocytes, which initiate the biosynthesis of antibodies.

However, an antigen is not the entire biopolymer molecule; only its specific "active" regions—known as antigenic determinants or epitopes—are antigenic, and The surface of an antigen may bear A large number of them. Each epitope within a given antigen molecule induces B Cells of The Immune System to synthesize specific Antibodies directed against it. Consequently, immunizing an animal yields antibodies of varying specificities. According to modern data, antibody diversity reaches 10⁷. This means that the animal Organism is capable of synthesizing and secreting into the bloodstream at least 10 million antibody molecules that specifically interact with different antigenic determinants.

Synthesized antibodies utilize their functionally active groups (receptors) to recognize and interact with epitope regions located On the surface of the antigen molecule. This interaction results in the attachment of the antibody to the corresponding antigenic epitope via its receptors, forming an antigen-antibody complex that neutralizes the biological activity of the foreign substance.

The Synthesis and Secretion of antibodies are carried out by a specialized type of lymphoid Cell—B lymphocytes. Each B lymphocyte synthesizes only a single type of antibody capable of interacting with just one epitope. As a result, the number of Different types of antibody-producing B cells generated equals the number of determinants on the antigen.

The body of higher vertebrates contains nearly 10 million distinct lineages of B lymphocytes that respond to signals from antigenic epitopes. A clone of plasma cells producing Monoclonal Antibodies originates from a single precursor B lymphocyte. However, even when antibodies are generated against a single epitope, the stimulation and proliferation of multiple B lymphocyte clones occur, synthesizing different antibodies. Consequently, this yields heterogeneous antibodies in the immune serum (antiserum)—essentially a mixture of antibodies directed against various epitopes. Such antibodies are referred to as polyspecific, or more commonly, polyclonal.