Basophils

Basophils belong to a category of white blood cells called granulocytes because they contain tiny granules. The granules in basophils are made up of different chemicals, including histamine and heparin. When needed, basophils break open (degranulate) to release these chemicals as part of the body's immune defense.

Basophils make up only around 1% or less of all white blood cells, but are among the largest. These cells not only provide frontline defense against infection, but are also involved in processes such as inflammation and allergy. Basophils also attack foreign agents indirectly by binding to a type of white blood cell called B-cell lymphocytes. The binding causes B cells to release antibodies called immunoglobulin (IgE) into the bloodstream. IgE has a strong action against parasites and venoms.