Immune system

The **immune system** is not a single molecule or receptor but rather a complex network of cells, tissues, organs, and molecular mediators that work together to protect an organism from disease. It consists of two main branches: *Innate immune system*: Provides immediate but non-specific defense against pathogens through mechanisms such as physical barriers, phagocytic cells (e.g., neutrophils, macrophages), pattern recognition receptors like toll-like receptors (TLRs), cytokines, chemokines, and the complement cascade. This branch does not confer long-lasting immunity but is essential for initial pathogen control[7]. *Adaptive immune system*: Mounts specific responses to antigens via lymphocytes—B cells produce antibodies while T cells mediate cellular immunity. Adaptive responses are slower to develop on first exposure but provide immunological memory for faster response upon re-exposure. Molecular components include antibodies of various classes (IgM, IgG, IgA, IgD, IgE), cytokines such as interleukins and interferons that regulate cell communication during immune responses; chemokines that direct cell migration; pattern recognition receptors like TLRs; antigen-presenting molecules such as MHC proteins; and numerous other soluble factors involved in inflammation or tolerance[1][2][7]. Because "Immune system" refers to an entire biological network rather than a discrete molecular target or receptor suitable for drug targeting in the conventional sense—and encompasses many different molecules with distinct roles—it is not considered a canonical therapeutic target itself. Instead, individual components within the immune system may serve as drug targets depending on context. If you are seeking information about a specific molecule within the immune system—such as "Programmed cell death protein 1" or "Interleukin 6 receptor"—please specify so structured data can be provided at the appropriate level of detail.

Other names

Immune systemHuman immune systemImmunological system