Newly discovered roles for basophils: a neglected minority gains new respect.

Basophils are the least common type of granulocyte and they account for less than 1% of peripheral blood leukocytes. Because of this minority status and a phenotype that is similar to mast cells, basophils have often been neglected in immunological studies or considered to have minor, redundant roles in immune responses in vivo. However, recent studies have now defined previously unrecognized roles for basophils in both immune regulation and allergic responses, and have shown that basophils and mast cells have distinct roles in immune responses.