About Basophils
Basophils are the rarest white blood cell type in circulation, making up less than 1% of all white cells, but they are central orchestrators of allergic and inflammatory reactions — releasing histamine, heparin, and other mediators when triggered by allergens or parasites. Elevated basophil counts (basophilia) are uncommon and can signal allergic reactions, inflammatory bowel disease, hypothyroidism, or, rarely, certain myeloproliferative disorders. Their low absolute count means even small absolute changes in basophil numbers are clinically meaningful.