Antibody Therapies & Biologics
Monoclonal and polyclonal antibodies — how they work and clinical examples
Antibodies are proteins produced by the immune system to recognise and neutralise foreign substances. Understanding how they work — and how they are engineered into medicines — is fundamental to modern pharmacy practice, from biological therapies in cancer and autoimmune disease to passive immunisation.
What are Antibodies?
Antibodies are proteins made by B cells (a type of white blood cell) in response to foreign substances called antigens. Each antibody is made of two heavy chains and two light chains joined together, forming a Y-shape. There are five classes of antibody: IgG, IgA, IgM, IgE, and IgD. IgG is the most abundant in the blood and is the class most commonly used in medicines — it has a long half-life and can cross the placenta to protect newborns.
Polyclonal vs Monoclonal Antibodies
Polyclonal antibodies are a mixture produced by many different B cell clones, each targeting a different part (epitope) of the same antigen. They provide broad coverage and are used in anti-toxins and passive immunisation. Monoclonal antibodies (MAbs) come from a single B cell clone and target one specific site on the antigen with high precision. Both types are used as medicines, but monoclonal antibodies have become particularly important in targeted therapy for cancer and autoimmune conditions.
How are Monoclonal Antibodies Made?
Monoclonal antibodies are produced using hybridoma technology. A B cell from an immunised animal is fused with a myeloma (cancer) cell to create a hybridoma — an immortal cell line that produces identical antibodies indefinitely. This allows large-scale manufacturing of highly specific, consistent antibody medicines. The hybridoma is screened to confirm it produces the correct antibody before being used for production.
From Mouse to Human — Reducing Immune Reactions
The first monoclonal antibodies were derived entirely from mice (murine), which caused immune reactions in patients. Over time, antibody engineering evolved to reduce this problem — progressing from chimeric (part mouse, part human) to humanised (mostly human with tiny murine regions) to fully human antibodies. Careful evaluation of antibody design is key to reducing side effects and improving tolerability. The naming convention reflects this evolution: -omab (murine), -ximab (chimeric), -umab (humanised), -mumab (fully human).