the absolute eosinophil count (AEC) is a blood test that measures the number of eosinophils in a person's blood. Eosinophils are a type of white blood cell that plays a role in the immune system's response to allergens, parasites, and certain infections. Measuring the absolute eosinophil count can help in diagnosing and monitoring various medical conditions, including allergies, asthma, autoimmune diseases, and parasitic infections.