Fagosit

Fagosit is a term used in immunology to describe immune cells that perform phagocytosis, the process of ingesting and digesting particulate matter such as microbes, dead cells, and debris. In humans, the primary fagosit cells are neutrophils and monocytes/macrophages; dendritic cells and, in some contexts, eosinophils also participate in phagocytosis. These cells originate from hematopoietic stem cells in the bone marrow and mature to function in blood and tissues.

Phagocytosis involves several steps. Recognition of targets occurs via receptors such as pattern recognition receptors, Fc receptors, and complement receptors. The target is bound and internalized to form a phagosome, which then fuses with lysosomes to create a phagolysosome. Microorganisms within the phagolysosome are killed and digested through mechanisms including reactive oxygen species, reactive nitrogen species, acidic pH, and lysosomal enzymes. Some fagosit also process and present antigens to T cells, linking innate and adaptive immunity.

Function and significance. Fagosit play central roles in defending the host against infections, removing cellular debris, and shaping immune responses. Macrophages and dendritic cells are particularly important for antigen presentation, which helps activate T cells. The activity of fagosit is regulated by inflammatory signals and the availability of opsonins such as antibodies and complement.

Clinical relevance. Defects in fagosit function or numbers can lead to increased susceptibility to infections. Example disorders include chronic granulomatous disease, caused by impaired killing within phagolysosomes, and severe neutropenia, which reduces phagocytic capacity. Treatments often focus on preventing infection and supporting immune function.