Monoclonal Antibodies

Monoclonal antibodies are homogeneous antibodies of a single specific type produced against one antigen.

• Traditional Method: Antibodies were traditionally isolated by injecting animals with antigens (hyper-immunisation) and extracting their serum.
• Drawback: This produced heterogeneous (mixed) antibodies because the animal's cells produce a variety of different antibodies. These lack the exact specificity needed for accurate medical diagnosis.
• The Solution: The development of monoclonal antibodies solved this problem by providing highly specific, pure antibodies.

• They are homogeneous (uniform and pure) immunological agents.
• They have a highly defined specificity, meaning they bind perfectly to one specific target.
• Because of their purity and accuracy, they are highly reliable for medical diagnosis and disease screening.

Monoclonal antibodies are artificially produced in specialised cells called hybridomas.

A hybridoma is a lab-created cell formed by fusing two different types of cells:

1. Lymphocyte Cell: An antibody-producing cell (e.g., a spleen cell from a mouse that has been immunised against a specific antigen, like sheep red blood cells).
2. Myeloma Cell: A bone marrow tumour cell (cancer cell) that has the ability to multiply indefinitely.

Properties of a Hybridoma: By fusing these two cells, the resulting hybridoma inherits two crucial abilities:

• The ability to produce specific antibodies (from the lymphocyte).
• The ability to grow and divide continuously (from the myeloma cell).

1. Immunisation: An antigen is injected into a mouse. Several doses are given over a few days to boost the mouse's immune response and antibody production.
2. Cell Collection: Lymphocytes (spleen cells) producing the desired antibodies are harvested from the mouse.
3. Cell Fusion: The extracted mouse spleen cells are fused with rat myeloma (tumour) cells.
4. Screening: The newly formed hybridoma cells are tested (screened) to find the ones that are successfully producing and secreting the required antibodies.
5. Culturing: The successful hybridoma cells are cultured (grown in large numbers) to mass-produce pure monoclonal antibodies for medical use.

Monoclonal antibodies are primarily used for immunoassay – a technique used to detect and estimate the exact quantity of a specific chemical in a complex mixture. Common applications include:

• Pregnancy Testing Kits: To detect specific pregnancy hormones present in urine.
• Drug Screening: To detect the presence of banned drugs or performance-enhancing chemicals in the urine of athletes.
• Disease Diagnosis: To detect the presence of specific pathogens, such as identifying the human immunodeficiency virus (HIV) in AIDS testing.

• Monoclonal antibodies are homogeneous antibodies of a single, specific type produced against one antigen.
• They are produced by hybridoma technology using fused antibody-producing lymphocytes and myeloma cells.
• Hybridoma cells combine continuous growth with the ability to secrete specific antibodies.
• Monoclonal antibodies are highly specific and therefore useful for accurate diagnosis and screening.
• They are widely used in immunoassays, pregnancy tests, drug detection, and diagnosis of diseases like AIDS.