Monoclonal Antibodies

We can break up the word monoclonal into two parts. ‘Mono‘ means one and ‘clonal‘ means an identical copy. So, monoclonal antibodies are identical copies of a single type of antibody. They are produced from clones of a unique white blood cell, which is called the parent cell.

Antibodies are proteins produced by a type of white blood cell called lymphocytes. Pathogens are recognised as foreign when they enter the body, so they are attacked by the lymphocytes.

There are proteins on the surfaces of pathogens called antigens. Antibodies are complementary to the shape of a specific antigen. They attach to the antigens, which immobilises the pathogens.

Illustration showing the interaction between a pathogen and an antibody. The large pink/orange circle represents the "Pathogen" with spiked protrusions. From this pathogen, two arrows point outwards, indicating two types of "Antigen", with the second named a "Different antigen". On the right side, a blue Y-shaped figure represents the "Antibody" targeting the antigens on the pathogen.

One type of antibody will bind to a matching antigen, so specific antibodies will attach to specific pathogens. Scientists discovered that antibodies can bind to antigens on the surfaces of other substances other than pathogens. So, antibodies have many uses.

Producing Monoclonal Antibodies

We can stimulate lymphocytes in mice to produce a particular monoclonal antibody in response to exposure to an antigen.

1. A mouse is injected with an antigen

2. Lymphocytes in the mouse will produce antibodies in response to the antigen

  • However, lymphocytes like this will not divide by mitosis

3. The lymphocytes are fused with tumour cells (also called myeloma cells) to form hybridoma cells

  • Tumour cells are effective at dividing by mitosis

4. The hybridoma cells formed produce antibodies to the original antigen and can divide by mitosis

5. A single hybridoma cell is extracted and is allowed to divide by mitosis, which forms identical clones of the original hybridoma cell

  • All of the identical clone cells produce identical antibodies, which are called monoclonal antibodies

6. A large amount of monoclonal antibodies is collected and purified

Illustration detailing the process of producing monoclonal antibodies using a mouse. A syringe injects an antigen into a mouse. The mouse then produces lymphocytes, represented by blue cells with purple nuclei. These lymphocytes are shown near green "Tumour cells". The two cell types then "Fuse together" to form "Hybridoma cells", depicted as blue cells with a single purple nucleus. Finally, these hybridoma cells produce "Monoclonal antibodies", illustrated as blue Y-shaped structures.

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