Mediate allergic reaction.

- Densely basophilic granules contain heparin (anticoagulant) and histamine (vasodilator) (vs histaminase in eosinophils).- Leukotrienes synthesized and released on demand.

- Basophilia can be a sign of myeloproliferative disease, particularly CML (vs eosinophilia in Hodgkin lymphoma).