Basophils are the least frequent of the 5 types of leucocytes, constituting less than 1% of circulating white cells. They last from a few hours to several days.
In the laboratory, basophils are differentiated from other leucocytes in by their ability to resist penetration by Lysercell in the WNR channel of Symex XN analysers. Basophils are slightly smaller than neutrophils and are characterised by many large dark staining granules which overlie the multilobed nucleus in Romanovsky stained slides.
Basophil Function
Basophils are attracted to micro-organisms or sites of inflammation due to the release of chemotactic substances. Phagocytosis then occurs and the micro-organism is surrounded by membrane and fused with a primary lysosome. This phagosome is then attacked by bactericidal proteins and hydrolytic enzymes.
Basophils release histamine, prostaglandins and leukotrienes to promote inflammation and have attachment sites for IgE coated antigens. When basophils enter the tissues they are known as mast cells.
Causes of a raised basophil count (basophilia):
Inflammation - Myxoedema, ulcertive colitis, hypersensitivity states.
Drugs - IL-23
Haematologic - Myeloproliferative/leukaemic disorders (especially CGL)