Eosinophils normally make up approximately 1–3% of white blood cells in the peripheral blood, and are about 12–17 micrometers in size. Eosinophils are a component of the innate immune system and they have been largely associated with defense against parasites and allergic reactions in the body. Eosinophils are granulocytes with granules containing major basic protein and eosinophil cationic protein. The release of these proteins by degranulation is a major mechanism for Eosinophils' effector function. Furthermore, eosinophils have been shown to exert regulatory functions by their large reserve of granule products, cytokines and growth factors, as well as to function as antigen presenting cell to T cells. In disease, Eosinophils are deemed a key orchestrator of asthma pathagenesis. Evidence has suggested that eosinophils take an active role in epithelial damage and basal membrane hyper-proliferation.

Our Human Normal Peripheral Blood Eosinophils are isolated from peripheral blood granulocytes by indirect immunomagnetic selection. All peripheral blood is collected in acid-citrate-dextrose formula A (ACDA) by leukapheresis from fully consented IRB approved donors that are tested negative for HIV, HBV, and HCV.