A monoclonal antibody (mAb) is an immunoglobulin produced by a single clone of plasma cells that recognizes one specific epitope. Unlike polyclonal antibodies that consist of a mixture of immunoglobulins targeting various epitopes, monoclonal antibodies are homogeneous in structure and specificity.
Production and Characteristics
The first monoclonal antibodies were generated using hybridoma technology, in which B cells from an immunized animal are fused with immortal myeloma cells to produce hybrid cells that secrete a single antibody indefinitely. Modern methods employ recombinant DNA and phage display libraries to engineer antibodies with desired affinity, human constant regions or bispecific properties. Monoclonal antibodies can be murine, chimeric, humanized or fully human, depending on the proportion of human sequence, which affects immunogenicity in patients. Because they originate from a single B cell clone, all molecules share identical variable regions and isotypes, resulting in uniform affinity and effector functions such as complement activation or Fc receptor binding. Engineering can enhance half‑life, reduce immune reactions, or fuse cytotoxic drugs or radionuclides to create antibody–drug conjugates.
Applications in Medicine and Research
Monoclonal antibodies are central to many diagnostic and therapeutic strategies. Clinically, mAbs are used to treat cancers by targeting tumour antigens (for example, rituximab against CD20 in B‑cell lymphomas, trastuzumab against HER2 in breast cancer and nivolumab as an immune checkpoint inhibitor). In autoimmune diseases, mAbs neutralize cytokines or block cell‑surface receptors, such as adalimumab against tumour necrosis factor‑α or natalizumab against α4‑integrin. Neutralizing monoclonal antibodies against viruses like SARS‑CoV‑2 and respiratory syncytial virus provide prophylaxis and therapy. In laboratories, monoclonal antibodies are indispensable reagents for western blots, flow cytometry and immunohistochemistry because of their specificity and reproducibility. Monoclonal antibodies also form the basis of many rapid diagnostic tests, including pregnancy tests and lateral flow assays. Monoclonal antibodies provide highly specific recognition of individual epitopes and have transformed biomedical research, diagnostics and therapeutics. Their controlled production and modifiable structures make them versatile tools across numerous disciplines. Related Terms: Hybridoma, Antibody, Epitope, Therapeutic antibodies, Humanized antibody