Immune suppression and activation

Immune suppression and activation is not a specific molecule or receptor but rather describes broad physiological processes involving numerous cell types, signaling molecules, and pathways that regulate the immune system. Immune activation refers to the stimulation of immune cells—such as T cells, B cells, macrophages, dendritic cells—leading to responses against pathogens or abnormal cells. Immune suppression involves mechanisms that dampen these responses to prevent tissue damage from excessive inflammation or autoimmunity. Key mediators of immune suppression include regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), M2-polarized macrophages (tumor-associated macrophages), and immunosuppressive cytokines like IL‑10 and TGF‑β[1][2][3]. These elements act through various mechanisms: - Secretion of inhibitory cytokines (e.g., IL‑10, TGF‑β) - Induction of cytolysis in effector immune cells by regulatory populations[2] - Modulation of antigen-presenting cell function[3] - Expression of checkpoint ligands such as PD-L1 that inhibit T cell activity[1][3] Conversely, immune activation is driven by pro-inflammatory signals, antigen presentation by dendritic cells/macrophages leading to lymphocyte proliferation/differentiation/effector function[7], production of activating cytokines like IFNγ/TNFα/IL‑12[4], and engagement with pathogen-associated molecular patterns via receptors such as Toll-like receptors. Because "immune suppression and activation" does not refer to a single defined target but rather encompasses many distinct molecules/receptors/cell types/processes involved in regulating immunity—and because it cannot be mapped directly onto a canonical therapeutic target—the entry is considered incorrect for structured target annotation purposes.

Not applicable; this term refers to complex physiological processes involving many molecules and pathways, not a single target for which a specific drug mechanism of action applies.