Definition and Origin:
Monoclonal antibodies (mAbs) are a type of protein made in the laboratory that can bind specifically to a unique site (antigen) on cells or other proteins.
The term “monoclonal” denotes that these antibodies originate from a single B-cell clone and thus share identical binding affinities and specificities.
Generation:
Historically, mAbs were produced by fusing an immortal myeloma cell line with a B-cell producing a specific antibody.
The resultant "hybridomas" could be cultured indefinitely, producing large quantities of a singular type of antibody.
With advances in biotechnology, there are now various methods to produce mAbs, including phage display and transgenic animals.
Background:
A. Antibodies:
Before diving into monoclonal antibodies, it's crucial to understand antibodies in general.
Antibodies are proteins produced by the body’s immune system in response to foreign substances or pathogens.
They can specifically recognize and bind to particular structures called antigens, found on the surface of pathogens or other foreign entities.
B. Polyclonal vs. Monoclonal:
When the body is exposed to a pathogen, it produces a mixture of different antibodies that target various parts of the pathogen; this mix is termed polyclonal.
Monoclonal antibodies (mAbs), on the other hand, are a population of antibodies that are identical because they are produced by clones of a unique parent immune cell and hence bind to a singular, specific site on the antigen.
Structure of monoclonal antibodies
mAbs, like all antibodies, possess a Y-shaped structure.
This comprises two identical heavy chains and two identical light chains.
The ends of the "Y" shape form the Fab region, which is responsible for antigen binding, while the stem of the "Y" forms the Fc region, dictating the antibody's interactions with cells and other molecules in the immune system.
Specificity:
One of the primary advantages of mAbs is their high specificity.
Through their Fab region, they can bind with high affinity to their target, often a specific protein or receptor on the surface of cells.
Production of Monoclonal Antibodies
Hybridoma Technology:
The primary technique for producing mAbs is the hybridoma technology.
It involves fusing an immune cell (B-cell) that produces the desired antibody with a myeloma (cancer) cell.
The resultant cell, called a hybridoma, is capable of both producing the desired antibody and replicating indefinitely.
By selecting a single hybridoma clone, scientists can produce large amounts of a single, specific monoclonal antibody.
