basofiilien

Basofiilien, commonly called basophils in English, are a type of white blood cell classified as granulocytes. They are the least abundant granulocytes in peripheral blood, typically making up about 0.5 to 1 percent of circulating leukocytes. Basofiilien develop in the bone marrow from myeloid progenitors and have a short lifespan in the circulation, often lasting only one to two days before migrating to tissues or undergoing turnover.

Morphology and granules: Basofiilien are small cells with a bilobed or indented nucleus obscured by numerous cytoplasmic granules. The granules stain intensely with basic dyes and contain mediators such as histamine, heparin, proteases, and a range of cytokines and growth factors.

Receptors and activation: They express the high-affinity IgE receptor FcεRI on their surface and can be activated by cross-linking of bound IgE by allergens or parasites. Upon activation, basofiilien release mediators through degranulation, including histamine, leukotrienes, and cytokines such as IL-4 and IL-13, which influence broader immune responses.

Functions: Basofiilien participate in inflammatory and allergic processes, contribute to defense against parasitic infections, and promote Th2-type immune responses. Through mediator release and cellular interactions, they modulate vascular permeability, smooth muscle tone, and recruitment of other immune cells, notably mast cells and eosinophils.

Clinical relevance: Basofiilien are normally rare in blood testing. Basophilia, an elevated basophil count, can occur in certain myeloproliferative disorders such as chronic myeloid leukemia and some inflammatory conditions. Basofiilien are counted in complete blood counts and can be identified by flow cytometry using markers such as FcεRI and CD203c.

Relation to mast cells: Basofiilien circulate in blood, whereas mast cells reside predominantly in tissues; both cell types store similar mediators and contribute to allergic and inflammatory responses.