eosinophil

Eosinophils are a type of white blood cell, specifically one of the granulocytes, and an important part of your immune system. They are made in the bone marrow and travel through the bloodstream, watching for trouble. While all white blood cells help fight infection, eosinophils have a more specific specialty: helping defend the body against parasites, especially larger ones such as worms. When they find a target, they release proteins from their internal granules to damage or kill the invader.

However, their role is not limited to parasite defense; they also play a major part in allergic reactions and asthma. When you encounter an allergen, such as pollen or pet dander, your body releases chemicals that attract eosinophils to the site of inflammation. While they are trying to help, this buildup can also add to tissue damage and symptoms such as swelling, itching, and narrowed airways.

Doctors often measure eosinophil levels in a blood test as part of diagnosing various conditions. A high eosinophil count (eosinophilia) can indicate parasitic infection, allergic disease, asthma, certain skin disorders, or even some types of cancer. Conversely, a low count (eosinopenia) can sometimes be seen during high-stress periods or with the use of corticosteroids. So, while you might not think about them every day, eosinophils are tireless defenders working behind the scenes to protect your body from harm—whether it's a microscopic worm or an irritating allergen!