MONOCLONAL ANTIBODIES are identical antibodies produced from a single clone of B-lymphocytes — they are all specific to exactly the same antigen.
Normal antibodies are polyclonal — a mixture of different antibodies made by different lymphocytes, each responding to slightly different parts of a pathogen.
Monoclonal antibodies are MONOSPECIFIC — they bind to one specific target molecule with very high precision. This makes them extremely useful tools in medicine, diagnosis and research.
Key property: because they are produced from a single clone, every antibody is IDENTICAL — same shape, same binding site, same specificity.
How Monoclonal Antibodies Are Produced
Producing monoclonal antibodies involves a clever combination of lymphocytes (which make antibodies but don't divide indefinitely) and tumour cells (which divide indefinitely but don't make useful antibodies).
STEPS:
1. Inject a mouse with the target antigen → the mouse's immune system produces specific lymphocytes.
2. Remove the lymphocytes from the mouse's spleen.
3. FUSE the lymphocytes with TUMOUR CELLS (myeloma cells) — this creates HYBRIDOMA CELLS.
4. Hybridoma cells divide indefinitely AND produce the specific antibody.
5. Select and clone the hybridoma cells that produce the desired antibody.
6. Culture the clone in large quantities → produces large amounts of identical monoclonal antibodies.
7. Purify and collect the antibodies.
Hybridoma cells are sometimes called 'immortal antibody factories' — they combine the antibody-producing ability of B-cells with the unlimited division of cancer cells.
Uses of Monoclonal Antibodies
PREGNANCY TESTS:
Detect the hormone hCG (human chorionic gonadotropin) — produced only during pregnancy.
Monoclonal antibodies specific to hCG are on the test strip.
If hCG is present in urine, it binds to the antibodies → produces a visible colour change.
Quick, accurate and specific — one of the most widely used diagnostic tests.
CANCER TREATMENT (targeted therapy):
Monoclonal antibodies can be designed to bind to SPECIFIC PROTEINS on cancer cell surfaces.
This can: block signals that tell cancer cells to divide; mark cancer cells for destruction by the immune system; or carry a drug/radioactive substance directly to the cancer cell (magic bullet therapy).
Example: Herceptin (trastuzumab) binds to HER2 receptors on some breast cancer cells — blocking tumour growth.
Advantage over chemotherapy: targets cancer cells specifically — less damage to healthy cells.
DIAGNOSTIC TESTS:
Used in lateral flow tests (e.g. COVID-19 LFTs, flu tests) — detect specific antigens quickly.
Used in blood tests to detect hormones, pathogens or cancer markers.
Used in research to locate specific molecules in tissues (immunohistochemistry).
SIDE EFFECTS:
Monoclonal antibodies can cause fever, rashes, joint pain, low blood pressure.
Some trigger allergic reactions — the immune system may respond to the foreign antibody proteins.
Long-term effects are still being researched for newer treatments.
⚠️ Common Mistake
Monoclonal antibodies are NOT the same as normal antibodies — they are IDENTICAL copies from ONE clone, all specific to ONE antigen. Normal (polyclonal) antibodies are a mixture. Also: monoclonal antibodies in cancer treatment target the cancer cells specifically — this is why they cause fewer side effects than chemotherapy (which kills all rapidly dividing cells).
📌 Key Note
Monoclonal antibodies: identical antibodies from one B-lymphocyte clone. Made by fusing lymphocytes with tumour cells → hybridoma cells. Uses: pregnancy tests (detect hCG), cancer treatment (targeted therapy), diagnostic tests (COVID LFT). More specific than chemotherapy.
🎯 Matching Activity — Match the Monoclonal Antibody Use
Match each use to how monoclonal antibodies are used. — drag the symbols on the right to match the component names on the left.
Pregnancy test
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Cancer treatment
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COVID lateral flow test
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Hybridoma cell
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Fused B-lymphocyte + tumour cell — divides indefinitely and produces specific antibodies
Antibodies bind to specific proteins on cancer cell surfaces — blocking growth or delivering drugs
Antibodies detect specific viral antigens — rapid diagnostic result
Detects hCG hormone — monoclonal antibodies bind to hCG in urine, producing a colour change
🎯 Test Yourself
Question 1 of 3
1. What is a hybridoma cell and why is it useful?
2. Why are monoclonal antibodies more targeted than conventional chemotherapy for cancer treatment?
3. A pregnancy test uses monoclonal antibodies specific to hCG. What does this mean?
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