What does an increase in eosinophils primarily indicate?

An increase in eosinophils is primarily associated with allergic reactions. Eosinophils are a type of white blood cell that play a crucial role in the body's immune response, particularly in combating parasites and mediating allergic responses. When the body encounters allergens, such as pollen, pet dander, or certain foods, the immune system activates and produces more eosinophils to help manage the reaction. This elevation in eosinophil levels is a marker of allergic conditions, including asthma, allergic rhinitis, and eczema.

While eosinophils can also be involved in responses to certain infectious diseases, particularly those caused by parasitic infections, their primary function is commonly linked to allergic mechanisms rather than direct responses to infectious agents or autoimmune activity. Therefore, recognizing eosinophilia as a hallmark of allergic reactions is essential in clinical settings to inform diagnosis and treatment strategies.