3D rendering of a basophil
Basophil among red blood cells
Anatomical terms of microanatomy|
The mast cell, another granulocyte, is similar in appearance and function. Both cell types store histamine, a chemical that is secreted by the cells when stimulated. However, they come from different cell lines. Mast cells usually do not circulate in the blood stream, but instead stay in connective tissue. Like all circulating granulocytes, basophils go from the blood into a tissue when needed.
How they work is not well understood. Basophils have protein receptors on their cell membrane which binds IgE, an immunoglobulin involved in macroparasite defence and allergy. They are found in unusually high numbers at sites of ectoparasite infection, for example, by ticks.