Eosinophils are a type of white blood cell that play a crucial role in the immune system. They are primarily involved in combating parasitic infections and are also important in allergic reactions. Eosinophils contain granules filled with enzymes and proteins that help to destroy pathogens and modulate inflammation. These cells are produced in the bone marrow and circulate in the bloodstream. When the body encounters allergens or parasites, eosinophils migrate to the affected tissues, where they release their granules to help fight off the invaders. Elevated levels of eosinophils can indicate conditions such as asthma, allergies, or parasitic infections.