makrofajlarn

Makrofajlar, or macrophages, are large phagocytic cells that form a core component of the innate immune system. They originate from monocytes, a type of white blood cell produced in the bone marrow, which migrate into tissues and differentiate into tissue-resident macrophages. Macrophages are widely distributed in organs and connective tissues, where they monitor for pathogens and debris.

Key functions include phagocytosis of microbes and apoptotic cells, digestion within lysosomes, and secretion of cytokines and chemokines that coordinate immune responses. They also act as antigen-presenting cells, processing and presenting fragments of pathogens on MHC class II molecules to helper T cells, linking innate and adaptive immunity. In tissue homeostasis, macrophages clear dead cells and participate in remodeling during development, wound healing, and regeneration.

Macrophages can adopt different functional states in response to signals from the environment. The classically activated M1 state promotes inflammation and microbicidal activity, while the alternatively activated M2 state supports tissue repair and anti-inflammatory responses. This dichotomy is an oversimplification, but it summarizes major activation patterns in infection and injury.

Several tissues host specialized macrophage populations, including Kupffer cells in the liver, alveolar macrophages in the lung, microglia in the brain, and resident macrophages in the spleen and lymph nodes. They can originate from circulating monocytes or be self-renewing within tissues. Colony-stimulating factors, notably CSF-1 (M-CSF), regulate their differentiation and survival.

Clinical relevance: Macrophage dysfunction or dysregulated activation contributes to infectious, inflammatory, and metabolic diseases. Tumor-associated macrophages influence cancer progression, while chronic activation is linked to atherosclerosis, rheumatoid arthritis, and other inflammatory conditions. Understanding macrophages is therefore central to immunology and pathology.