Granulocyt

Granulocyt, more commonly referred to as a granulocyte, is a white blood cell characterized by the presence of cytoplasmic granules. The term is sometimes used in older or shorthand contexts, but the standard term in modern hematology is granulocyte. Granulocytes are produced in the bone marrow from the myeloid lineage and include neutrophils, eosinophils, and basophils. They circulate briefly in the bloodstream and then migrate into tissues as needed.

Neutrophils are the most abundant granulocytes and are key responders to bacterial infection. They phagocytose and destroy pathogens and release enzymes to combat microbes. Eosinophils participate in defense against parasites and play a role in allergic reactions and wound healing. Basophils, which are the least common of the three, release histamine and other mediators during inflammatory responses and can influence allergic reactions.

Granulocytes are regulated by growth factors such as granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF), which stimulate their production and maturation in the bone marrow. Abnormal granulocyte counts can indicate health problems: granulocytosis denotes an elevated granulocyte count, often related to infection or inflammation; granulocytopenia or agranulocytosis denotes a substantially reduced count, increasing susceptibility to infections. Clinically, granulocytes are typically assessed as part of a complete blood count with differential, which estimates the proportion and absolute numbers of neutrophils, eosinophils, and basophils.

Granulocyt refers to a class of cells rather than a single cell type, and understanding their roles aids in interpreting immune and hematologic conditions.