Makrofaagide

Makrofaagide (macrophages) are a type of large phagocytic cells that form a central part of the innate immune system. They arise from monocytes that migrate from the bloodstream into tissues, where they differentiate into tissue-resident macrophages such as Kupffer cells in the liver, microglia in the brain, alveolar macrophages in the lungs, and various splenic or peritoneal macrophages. Some macrophages are long-lasting residents, while others are recruited during inflammation to help coordinate responses.

Key functions of makrofaagide include phagocytosis of pathogens and dead cells, efferocytosis (clearance of apoptotic cells), and the production of reactive oxygen and nitrogen species for microbial killing. They also act as antigen-presenting cells by expressing MHC class II molecules and co-stimulatory signals to activate T cells. In addition, makrofaagide secrete a wide range of cytokines and chemokines, shaping both local and systemic inflammation, and they contribute to tissue remodeling and wound healing. They express various receptors, including pattern-recognition receptors such as Toll-like receptors and scavenger receptors, enabling detection of microbial components and damaged tissue.

Macrophages can polarize into different activation states. Classically activated M1 macrophages respond to IFN-γ and microbial products, promoting inflammation and antimicrobial defense. Alternatively activated M2 macrophages participate in tissue repair and resolution of inflammation, secreting anti-inflammatory mediators such as IL-10 and TGF-β. In disease contexts, makrofaagide contribute to conditions such as atherosclerosis, obesity-related inflammation, and cancer, where tumor-associated macrophages often adopt pro-tumor roles.