Eosinophils

A type of WBC seen in peripheral blood and tissue. It belongs to the myeloid lineage and more specifically a subtype of granulocyte with bright eosinophilic (red) granules containing Major Basic Protein, histamine, and plasminogen. Increased numbers of eosinophils in blood can be due to many things (remember the major classes for most differential diagnosis include an underlying Infection, Malignancy, autoimmune, trauma, congenital, drug-induced or idiopathic). Increased eosinophils may be due to an infection (e.g. tissue invasive parasites), Malignancy (e.g. Hodgkin lymphoma, Carcinoma or Chronic Eosinophilic Leukemia), Autoimmune, Drug-induced (e.g. certain antibiotics, etc.), or idiopathic.