American Association of Critical-Care Nurses (AACN) Certification Practice Test

Eosinophils play a crucial role in the immune response, particularly in combating allergens and parasitic infections. These white blood cells are part of the body's innate immune system and are particularly effective against larger invaders that are too big for standard phagocytosis, such as helminths (worms) and certain protozoa. When eosinophils encounter allergens, they release various cytokines, enzymes, and toxic granules that can directly damage or kill pathogens. Additionally, they contribute to the inflammatory response associated with allergic reactions, which can include conditions such as asthma and hay fever. Their ability to release inflammatory mediators makes them essential in the defense against parasites and in mediating allergic responses, distinguishing their primary role in the immune system.