[communicable disease] monoclonal antibodies

[ BBC Bitesize 'Infection and Response ⇢ Monoclonal antibodies' page 1-3 ]

Monoclonal Antibodies

Clones of antibodies from a single parent cell and are able to bind to specific antigens. They are identical copies of one type of antibody.

Hybridoma Cells

Cells formed by the fusion of lymphocytes and tumour cells.

Hybridoma Cell Features:

• undergo mitosis rapidly

• produce monoclonal antibodies

Antibody

A protein produced by white blood cells that attack foreign organisms (antigens) that get into the body.

Lymphocytes

White blood cells which attack pathogens by producing antibodies.

How Lymphocytes Work:

1. pathogen enters body and has proteins on their surface called antigens

2. lymphocytes recognise these antigens as foreign

3. lymphocytes attack pathogens by producing antibodies

1st Stage of Producing Monoclonal Antibodies

Antigens of a pathogen or the entire pathogen is injected into a mouse.

2nd Stage of Producing Monoclonal Antibodies

The mouse will produce lymphocytes, which will produce specific antibodies to attack and bind to these specific antigens. These lymphocytes are unable to divide and undergo mitosis.

3rd Stage of Producing Monoclonal Antibodies

Tumour cells, which are able to divide but are unable to produce antibodies, are extracted and fused with the lymphocytes extracted from the mouse.

4th Stage of Producing Monoclonal Antibodies

As a result, hybridoma cells are produced. These cells make antibodies and can divide by mitosis.

5th Stage of Producing Monoclonal Antibodies

These hybridoma cells are cloned, producing monoclonal antibodies which bind to the original pathogen’s antigen. They are cloned to produce many identical cells that all produce the same antibody.

6th Stage of Producing Monoclonal Antibodies

These monoclonal antibodies need to be separated, collected and purified before use.

Myeloma Cells

Cancerous white blood cells used in the formation of monoclonal antibodies. (Apparently)

Using Monoclonal Antibodies to Treat Cancer:

• can be designed to bind specifically with cancer cell antigens, making it easier to identify a cancerous tumour, which can then be treated or removed

• they encourage your immune system to attack the cancer cells directly

• they can block receptors on the surface of cancer cells, which stops them from growing and dividing by mitosis

• these antibodies can carry drugs or radioactive therapies to the cancer cells directly, without harming other cells

Pregnancy Tests:

• monoclonal antibodies are designed to bind with the hormone HCG, found only in pregnant women's urine

• monoclonal antibodies are attached to the end of a pregnancy test stick

• If pregnant, HCG in urine binds to the monoclonal antibodies on the test stick, which causes a change in colour or pattern, indicating pregnancy.

Diagnostic Uses of Monoclonal Antibodies:

Monoclonal antibodies are also used in a similar way to identify and diagnose infections, such as HIV and AIDS, herpes and chlamydia.

• to measure the levels of hormones and other chemicals in blood, or to detect pathogens

• to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye, that will glow under UV light, making disease identification much easier

Advantages of Monoclonal Antibodies:

• healthy cells are not affected, only the specific target cells with the specific antigens that the monoclonal antibodies can bind to

• can treat and diagnose a wide range of conditions

• doctors can treat side effects

• cheaper to produce than conventional drugs

Disadvantages of Monoclonal Antibodies:

• relatively expensive to produce

• create more side effects than expected

• not yet as widely used as everyone hoped when they were first developed

• difficult to produce

• ethical and religious issues; animal cruelty, serious issues in its human trials