Monoclonal Antibodies: Monoclonal antibodies are created by identical immune cells that are all clones of a singular parent cell. As they have monovalent affinity, they bind to the identical epitope (the part of an antigen recognized by the antibody).
Polyclonal Antibodies: Polyclonal antibodies are antibodies that bind to multiple epitopes and are typically created by many totally distinguished B-cells.
Hybridoma Technology: Hybridoma technology is the methodology of the production of large number of identical antibodies known as monoclonal antibodies.
Cesar Milstein and Georges J.F. Kohler invented the production of monoclonal antibodies in 1975 for which they got the Noble Prize of 1984 for Medicine and Physiology along with Niels Kaj Jerne, who made other contributions to immunology. The term hybridoma was introduced by Leonard Herzenberg in 1976-1977.
Principle: The method starts by injecting a mice with immunogen. The mice should response to immunogenic reaction. A kind of somatic cell, the B-cell, produces antibodies that bind to the immunogen. These recently created antibodies are then collected from the mice. These isolated cells are merged with immortal B-cells (a myeloma cell), in order to provide a hybrid cell known as Hybridoma. These hybridomas have the antibody producing ability of the B-cell and also have the reproducibility and longevity. The hybridomas are fully grown in culture medium. In addition, the manufactured antibodies are all chemically identical in distinct to polyclonal antibody.
Hybridoma Production of Monoclonal Antibody: The production of monoclonal antibody requires several steps involving,
1. Immunization: Firstly immunogen is injected into the laboratory mice. It is mixed with suitable adjuvant priorly and injected subcutaneously or intradermally. This injection procedure should be in repeated manner. Blood sample is taken and assayed for determining the presence of the desired antibody. If the antibody is present and in desired amount then the mice is sacrificed. It’s spleen is then disintegrated into spleenocytes.
2. Cell Fusion: In this step the acquired spleenocytes are fused with plasmacytoma cells. This fusion takes place in a suitable medium like PEG (Polyethelyn Glycol). The concentration of the medium must be high (about 50%). This mixture will later form the Hybridoma.
3. Selection: In the selection step the fused cells are incubated in HAT medium (Hypoxanthine-Aminopterine-Thymidine medium) for 10-14 days. The vialble Hybridoma cells are formed in this medium, Afterwards, they are transferred to a regular culture medium. The incubated medium is then diluted into multi-properly plates (96-well plastic culture plate) to such an volume that every well contain only one cell. The medium in each well is examined periodically.
4. Screening: The next step is a speedy primary screening test, in which the most effective hybridomas that produce antibodies of suitable specificity are identified. This screening is done by ELISA test. Antigen is applied in the bottom of the well of culture plates. Samples of produced antibody is incubated in the wells. We know that antigen-antibody bind together. So, if the desired antibody is present in the sample then it’ll bind with the antigen and stay in the plates. While washing, the bound materials are retained and the unbound materials are washed away.
5. Cloning: The B-cell that produce the desired antibodies can be cloned to produce many same daughter clones. The cloning techniques are Limiting Dilution Method and Soft Agar Method. They can be used individually but most of the cases used in combination.
In limiting dilution method, 96-well plastic culture plate is used for cloning, The hybridoma cells are diluted and each cell is placed in each well. This process is repeated and it ensures that monoclonality is attained.
In the alternative method, hybridoma cells are cloned in a single plate containing soft agar medium wherr the cells form spherical colonies.
6. Characterization and Storage: The monoclonality of the antibodies is established by biomedical and biophysical characterization of the antibodies using spectrometric, electrophoretic an chromatographic methods. The suitability and stability of the antibodies for therapeutic an diagnostic purpose is determined through this process.
Antibodies are preserved in frozen liquid nitrogen. Some are stored for running the further cloning process.
1. Diagnostic applications in CVS diseases, Deep vein thrombosis, Atherosclerosis, Infectious diseases, Cancer etc.
2. Therapeutic applications in Radioisotope conjugates, Toxin and drug immunoconjugates, Organ transplantation, Bone marrow transplantation, Autoimmune disease and so on.
3. Clinical applications
4. Preparative applications