Paper I
2024 June (Supplementary) (2019 Scheme) · 100 marks · 180 min

Question

Discuss applications of monoclonal antibodies.

Q68 marksShort Essays

Answer

Monoclonal antibodies (MAbs): antibodies produced by a single clone of B lymphocytes (or, industrially, by hybridoma technology — fusing an antibody-producing B cell with an immortal myeloma cell), and therefore identical in structure and directed against a single, specific epitope.

Applications of monoclonal antibodies:

  1. Diagnostic applications

    • Immunoassays (ELISA, immunofluorescence, immunohistochemistry) for detecting specific antigens/pathogens with high specificity (e.g., rapid antigen tests for infections, tumour marker assays).
    • Blood group typing and cross-matching reagents.
    • Flow cytometry — identifying and quantifying specific cell surface markers (e.g., CD4 count in HIV monitoring, leukaemia/lymphoma immunophenotyping).
  2. Therapeutic applications

    • Cancer therapy — targeting tumour-specific antigens (e.g., Rituximab against CD20 in B-cell lymphoma; Trastuzumab against HER2 in breast cancer).
    • Autoimmune/inflammatory disease — e.g., Infliximab/Adalimumab (anti-TNF-α) in rheumatoid arthritis and inflammatory bowel disease.
    • Transplant rejection prevention — e.g., Muromonab-CD3 (anti-CD3), used historically to prevent/treat acute organ transplant rejection.
    • Infectious disease — e.g., Palivizumab, used for prophylaxis against respiratory syncytial virus (RSV) infection in high-risk infants; monoclonal antibody cocktails used in some viral infections (e.g., COVID-19, Ebola).
    • Passive immunization — providing immediate, targeted antibody-mediated protection in specific high-risk clinical scenarios.
  3. Research applications

    • Identification and characterization of cell surface receptors/antigens.
    • Tools for protein purification (immunoaffinity chromatography) and molecular biology techniques (Western blotting).

Advantages of monoclonal over polyclonal antibodies: high specificity for a single epitope (reducing cross-reactivity), reproducible/consistent from batch to batch, and can be produced in unlimited quantity once a hybridoma cell line is established.

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