what are basophils

Basophils are a type of white blood cell that are part of the immune system. They are the least common type of granulocyte, representing about 0.5% to 1% of circulating white blood cells. Basophils are created inside the bone marrow and are the largest type of granulocyte. They contain anticoagulant heparin, which prevents blood from clotting too quickly, and the vasodilator histamine, which promotes blood flow to tissues. Basophils play an important role in helping the body respond to allergic reactions. During an allergic reaction, basophils release histamine and heparin, which can trigger symptoms such as a runny nose, sneezing, and coughing. Basophils also play a part in "immune surveillance," meaning they have the ability to help detect and destroy some early cancer cells. Basophilia is a sign that the body is producing too many basophils, which can be caused by a variety of medical conditions.