Basophils

Basophils are the least abundant granulocyte in circulation. They contain large granules with histamine, heparin, and other mediators. They are primarily effector cells in allergic reactions and defense against parasites. When activated by IgE cross-linking or other stimuli, they degranulate, releasing inflammatory mediators that contribute to symptoms like vasodilation, itching, and bronchoconstriction. They also influence immune responses by secreting cytokines like IL-4.