Immunomodulators

Introduction & terminology

• Immunomodulator — umbrella term for any agent that alters (up- or down-regulates) the magnitude, quality or specificity of an immune response; this topic focuses on the up-regulating arm.
• Immunostimulant / immunopotentiator — an agent that enhances host immune responsiveness — the primary subject; used in cancer immunotherapy, chronic/refractory infection and immunodeficiency states.
• Biological response modifier (BRM) — a recombinant protein, cytokine or monoclonal/polyclonal antibody that modifies the biological response to tumour cells — combining a direct inhibitory effect on malignant cells with reinforcement of immunological defence (e.g. IFN-α2, IL-2, TNF).
• Immunoadjuvant — a substance co-administered with antigen to amplify the magnitude, quality and duration of the adaptive response by first engaging the innate immune system.
• Directionality, not chemistry, defines the class — blocking an inhibitory checkpoint (PD-1, CTLA-4) stimulates immunity (cancer therapy), whereas blocking a stimulatory cytokine (TNF-α, IL-6) suppresses it (autoimmune disease) — the same molecular toolkit, opposite directions.