granülosit

Granülosit, often referred to in English as granulocytes, are a category of white blood cells characterized by cytoplasmic granules that stain with histochemical dyes. They are part of the innate immune system and are formed in the bone marrow from myeloid lineage cells. In humans, the term generally encompasses three main types: neutrophils, eosinophils, and basophils.

Neutrophils are the most abundant granulocytes, with a multi-lobed nucleus and fine granules; they act as first responders to bacterial infection, performing phagocytosis and releasing antimicrobial substances. Eosinophils have a bilobed nucleus and red-orange granules; they defend against parasitic infections and participate in allergic responses, releasing enzymes and mediators. Basophils contain large dark granules and play a role in inflammatory and allergic reactions by releasing histamine and other mediators; they also participate in modulating immune responses.

Granulocytes develop in the bone marrow through stages including myeloblasts and promyelocytes before maturing into segmented neutrophils, eosinophils, or basophils; after release, neutrophils circulate for about 6-8 hours and then migrate to tissues where they may survive days, while eosinophils and basophils have longer tissue lifespans. The granules contain enzymes and reactive substances used in defense, such as myeloperoxidase, major basic protein, and various proteases.

Abnormal granulocyte numbers reflect health status. Neutrophilia occurs during infection or inflammation, neutropenia can predispose to infection, and eosinophilia or basophilia can accompany allergic or parasitic conditions. Complete blood counts and differential leukocyte counts quantify granulocyte levels and aid diagnosis and monitoring of hematologic and inflammatory diseases.