Antibodies are glycoprotein structures that can identify foreign bodies such as bacteria and viruses and prompt a neutralizing immune response when antigens are detected in the body. B lymphocytes secrete immunoglobulins in response to aid in their destruction.
In addition to being critical in the immune response, antibodies are essential in research and diagnostic purposes. Their high specificity makes them powerful tools in detecting and quantifying a wide range of targets, including drugs, serum proteins, and microorganisms.
Antibody engineering has evolved, and today’s antibody drugs have significantly fewer adverse effects because of their high specificity. As a result, therapeutic antibodies have become a predominant category of new drugs being developed recently. Their potential in treating and preventing infectious diseases is enormous.
The first monoclonal antibodies(mAbs) emerged from the study of hybridomas; nowadays, researchers produce mAbs using these cells. Technology advancement has allowed antibody production to scale up and market introduction.
What is Antibodies Production?
Antibodies production is a term used to describe the process of developing antibodies. This involves immunogen preparation, immunization, hybridoma production, screening, and purification.
There are various techniques of antibodies production that have emerged. In vitro technique works for monoclonal antibodies production by use of hybridoma cells. Conversely, rabbits are used in polyclonal antibodies production.
Natural Antibody Production
Natural antibodies are the first line of defense against potential antigens. They are constantly available, and unlike adaptive antibodies, they are present in a germ-free environment.
Some of the main characteristics of natural antibodies include high avidity, polyreactivity, autoreactivity, and moderate anti-microbial affinity.
The common natural antibodies in humans include immunoglobulin M (IgM), IgA and its isotypes IgA1, IgA2, and IgG, including IgG1, IgG2, IgG3, and IgG4. Although their amounts reduce as you age, they are critical in preventing various illnesses like autoimmune disease and inflammation.
Adaptive Antibody Production
The adaptive immune system is activated when natural antibodies fail to act on antigens and control the infection. There are two types of adaptive systems: Humoral immune response and cell-mediated immune response.
Whereas the activities of T cells influence the cell-mediated immune response, the humoral immune response is dependent on the actions of both adaptive antibodies and B cells.
The adaptive antibodies are only activated after the antigens bind into the B-cell receptor(BCR) of B2 lymphocytes. When the antigen binds into the B cell, it triggers the production of specific cytokines causing fast proliferation of B cells.
Monoclonal Antibody Production in Mice
Since discovering the hybridoma technique of producing monoclonal antibodies(mAb), it has become a powerful tool in biological studies and clinical medicine.
Here are the steps of the typical mAb production process:
- Immunization of mice and isolation of B cells: Scientists immunize mice with an antigen and screen their blood for antibody production. The isolation of B cells for in vitro hybridoma production follows.
- Myeloma cells preparation: Here, myeloma cells are set up for fusion. Myeloma cells are immortalized cells that result in hybridoma with unlimited growth when fused with spleen cells.
- Fusion: Myeloma cells and B cells are fused to create hybridomas using polyethylene glycol(PEG), causing membranes to fuse.
- Clone screening and selection: The clones are screened and picked on antigen specificity and immunoglobulin class criteria.
- Characterization: Confirmation, validation, and characterization using different functional assays, e.g., ELISA, each potentially high-producing colony.
- Scale-up and wean: To produce the necessary antibodies needed, wean off the selection agent.
- Expansion: Expand clones to produce required antibodies; this is achievable through bioreactors or large flasks.
Polyclonal Antibody Production in Rabbits
Producing polyclonal antibodies involves immunizing lab animals like rabbits with antigens. The antibodies are later retrieved from the antiserum. Injection of antigens is carried out repeatedly to obtain higher titers of antibodies.
The production of polyclonal antisera is more straightforward and economical than mAbs production. Also, it takes a significantly shorter time to produce polyclonal antibodies than it is to produce monoclonal antibodies.
Antibody Production in Bacteria
E. coli is the most commonly used bacterial host to produce antibodies. An E. coli system offers various advantages that make it the most preferred among the researchers, such as fast cell growth and rapid new production cell lines. Also, it has no concern for foreign agents, which is not the case in other systems like mammalian cell systems, making viral removal and validation steps unnecessary.
Antibody Production in CHO Cells
CHO(Chinese Hamster Ovary) cells are widely used in recombinant protein and mAbs production. The CHO expression system is excellent because it can quickly adapt to various cultural conditions and is manipulatable by genetic engineering.
Purification of Antibodies
After production, antibodies are still required to undergo a purification process. This process includes centrifugation, filtering, and other isolation techniques. In centrifugation, whole cells and fragments are removable from the solution. Other methods may involve passing through an ion-exchange chromatography column, whereby antibodies separate by binding to specific ligands.
The production of antibodies has evolved a lot with the discoveries of new techniques regarding technological advancement. As a result, the biochemistry industry has benefited and made it possible for the large-scale production of antibodies for commercial purposes.