monoclonal antibody
Summary
Monoclonal antibodies (mAbs) are laboratory-produced antibodies derived from a single B-cell clone, engineered to bind a specific epitope on a target antigen with high specificity. They are widely used therapeutically (e.g., cancer, autoimmune disease, infections) and diagnostically (e.g., ELISA, flow cytometry). Nomenclature suffixes indicate their origin (e.g., -ximab = chimeric, -zumab = humanized, -mumab = fully human).
Detail
Monoclonal antibodies are produced using hybridoma technology (originally developed by Köhler and Milstein), which fuses an antibody-producing B cell with an immortal myeloma cell line to create a hybridoma capable of indefinite production of a single, identical antibody targeting one specific epitope. Modern production often uses recombinant DNA technology and phage display to create humanized or fully human antibodies, reducing immunogenicity (human anti-mouse antibody, HAMA response) seen with older murine-derived antibodies.
Clinical uses span oncology, rheumatology, immunology, and infectious disease: - Oncology: rituximab (anti-CD20, B-cell lymphomas), trastuzumab (anti-HER2, breast cancer), bevacizumab (anti-VEGF, antiangiogenic), cetuximab (anti-EGFR, colorectal cancer), pembrolizumab/nivolumab (anti-PD-1, checkpoint inhibitors) - Autoimmune/inflammatory disease: infliximab/adalimumab (anti-TNF-alpha, Crohn's, RA, psoriasis), natalizumab (anti-alpha4-integrin, MS), omalizumab (anti-IgE, asthma), ustekinumab (anti-IL-12/23, psoriasis) - Transplant: basiliximab (anti-IL-2 receptor, prevents rejection) - Infectious disease: palivizumab (anti-RSV, prophylaxis in high-risk infants) - Cardiology: PCSK9 inhibitors like evolocumab and alirocumab for hyperlipidemia - Diagnostics: used in ELISA, Western blot, flow cytometry, immunohistochemistry for detecting specific antigens
Mechanisms of action vary: some mAbs block ligand-receptor interactions (bevacizumab-VEGF), some induce antibody-dependent cellular cytotoxicity (ADCC) or complement-mediated lysis (rituximab), some deliver conjugated toxins/radioisotopes (brentuximab vedotin, ado-trastuzumab emtansine), and immune checkpoint inhibitors unleash T-cell mediated tumor killing.
Naming conventions (WHO INN system) reflect antibody origin: -omab (murine), -ximab (chimeric, ~65-90% human), -zumab (humanized, >90% human), -mumab or -umab (fully human). The target is indicated by an infix (e.g., -ci- for circulatory, -li- for immune, -tu- for tumor).
Adverse effects include infusion reactions, increased infection risk (especially with TNF-alpha inhibitors—reactivation of latent TB, hepatitis B), progressive multifocal leukoencephalopathy (natalizumab, risk with JC virus), and cytokine release syndrome (especially with T-cell engaging therapies like blinatumomab or CAR-T related products). Monoclonal antibodies against checkpoint inhibitors (PD-1/PD-L1, CTLA-4) can cause immune-related adverse events due to breaking self-tolerance (colitis, pneumonitis, endocrinopathies).
Sources
- First Aid for the USMLE Step 1
- Katzung's Basic and Clinical Pharmacology
- Kuby Immunology
- Robbins and Cotran Pathologic Basis of Disease
- UpToDate
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