A type of white blood cell (leucocyte) that has a lobed nucleus surrounded by granular cytoplasm (see granulocyte). Basophils are produced continually by stem cells in the red bone marrow and move about in an amoeboid fashion. Normally present in very low numbers in the circulation, they may act in a similar manner to eosinophils in killing antibody-coated parasites. They accumulate with eosinophils at sites of allergic reactions and release histamine.