Innate immune system and antigen-presenting cells (Innate Immunity/APCs)

The innate immune system and antigen-presenting cells (APCs) constitute the body's primary defense mechanism and the essential bridge to adaptive immunity. APCs, such as dendritic cells, macrophages, and B cells, are responsible for capturing, processing, and presenting antigens via Major Histocompatibility Complex (MHC) molecules to T cells, providing the necessary signals for T cell activation and differentiation (StatPearls, 2023). This system utilizes pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), to identify pathogen-associated molecular patterns (PAMPs) and initiate inflammatory responses (NIH, 2022). In modern pharmacology, this system is a major focus for immunotherapy; for instance, TLR agonists are used to stimulate APCs in cancer treatment, while costimulatory blockers like Abatacept target APC-T cell interactions to treat autoimmune diseases (Nature Reviews Drug Discovery, 2021). Because this entry refers to a broad physiological system and a collection of cell types rather than a single molecular entity like a receptor or enzyme, it is classified as a biological system rather than a discrete therapeutic target.

Other names

Innate immunityAntigen-presenting cellsAPCsMyeloid lineage cellsProfessional antigen-presenting cells

Modulation of pattern recognition receptors (PRRs), costimulatory molecule signaling (e.g., CD80/86), and cytokine-mediated recruitment and activation of myeloid cells to enhance or suppress immune responses.