Monoclonal Antibodies

[Hybridoma Tecchnique]

Most fantastic and wonderful use of cancer cells of lymphoid tissue called Myeloma in combination with plasma B cells of spleen came into light after the discovery of an enigmatic biomolecule – Monoclonal antibody. It not only helps to diagnose the tumour (cancer) but also to remove it without harming neighbouring normal cells.

These wonderful biomolecules are obtained from clone produced from single cell called Hybridoma and recognize only one kind of specific antigen (pathogen), hence called monoclonal antibodies.

The idea of producing monoclonal antibodies by involving human–mouse hybrid cells was first described by Jerrold Schwaber in 1973. Later three Scientists  Georges Kohler, Cesar Milstein and Niels Kaj Jerne (1975) while working on these immunoglobulin,  developed a technique for producing monoclonal antibodies for which they were awarded Noble prize in1984. The technique used for producing these unique immunoglobulin involves following steps:

1                 A mouse is inoculated with specific  desired antigen that induces the production of antibodies against antigen.

2                 Now plasma B- cells from spleen of immunized mouse are removed from suspension which have developed the ability to produce antibodies.

3                 These spleen B – cells are then mixed with cancer cells of lymphoid tissue called Myeloma cells which have an ability to proliferate indefinitely and grow continuously.

4                 The plasma B – cells and myeloma cells are fused together to form hybrid cells called HYBRIDOMA. These hybrid cells are capable of growing indefinitely in culture and producing antibodies of single type continuously.

5                Hybridoma cells are isolated through selective medium called HAT medium because it contains Hypoxanthine, Aminopterin and Thymidine. Unfused myeloma cells fail to grow on this media because they lack an enzyme hypoxanthine-guanine-phosphoribosyl transferase (HGPRT).

Since immortal Hybridoma clone  is developed from single cell, all cells of clone are genetically identical and produce one type of antibody called monoclonal antibody. As compared to ordinary antibodies, monoclonal antibodies are more uniform and pure. Therefore, they are highly specific and are used to pinpoint the antigen present on surface of parasites.

Because of great affinity and specificity to a particular antigen, these are more effective and ideal for diagnosis as well as treating many diseases. Monoclonal antibodies can be used as highly efficient diagnostic tool for identification of specific pathogen/antigen. When a monoclonal antibody conjugated with a fluorescent dye is injected in patient ,it reaches to and gets attached with specific antigen present in a particular tissue/organ which can be scanned to detect the occurrence of pathogen/antigen.  A number of diagnostic kits like GONOZYME and CHLAMYDIAZYME have been developed by using monoclonal antibodies to identify Gonorrhoea and Chlamydial urethritis respectively.

Monoclonal antibodies are very effective in treating tumours. When monoclonal antibodies against tumour antigens are injected in patient’s body, they reach to and react specifically with tumour cells and destroy them without affecting other normal cells. These antibodies may be tagged with certain drugs and will remove only cancer cells specifically without harming other tissues

Monoclonal antibodies play an important role in organ transplant as these are used to reduce the chances of organ rejection by modifying/suppressing auto immune response after organ transplant. These are also used for cleansing bone marrow before transplant in treating immune system disorder.

Recap: Discovery of the wonderful and enigmatic biomolecule called monoclonal antibody was made by George Kohler and C Milstein (1975) for which they shared Noble prize (1984). These antibodies are synthesized from a clone of Hybridoma which is formed from the fusion of Myeloma and immunized B cell. It recognizes only one kind of specific antigen. Because of great affinity and specificity to a particular antigen these are used as an effective diagnostic tool and medicine for many diseases like tumour, gonorrhea and autoimmune disorder etc.