What are the functions of eosinphils?

Answer 1

From Wikipedia, the free encyclopediaEosinophil under the microscope (40x) from a peripheral blood smear. Red blood cells surround the eosinophil, two platelets at the top left corner.

Eosinophil granulocytes, usually called eosinophils (or, less commonly, acidophils), are white blood cells that are one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. Along with mast cells, they also control mechanisms associated with allergy and Asthma. They are granulocytes that develop during haematopoiesis in the bone marrow before migrating into blood.

These cells are eosinophilic or 'acid-loving': Normally transparent, they appear brick-red after staining with eosin, a red dye, using the Romanowsky method. The staining is concentrated in small granules within the cellular cytoplasm, which contain many chemical mediators, such as histamine and proteins such as eosinophil peroxidase, ribonuclease (RNase), deoxyribonucleases, lipase, plasminogen, and major basic protein. These mediators are released by a process called degranulation following activation of the eosinophil, and are toxic to both parasite and host tissues.

In normal individuals eosinophils make up about 1-6% of white blood cells, and are about 12-17 micrometers in size.[1] They are found in the medulla and the junction between the cortex and medulla of the thymus, and, in the lower gastrointestinal tract, ovary, uterus, spleen, and lymph nodes, but not in the lung, skin, esophagus, or some other internal organs [vague] under normal conditions. The presence of eosinophils in these latter organs is associated with disease. Eosinophils persist in the circulation for 8--12 hours, and can survive in tissue for an additional 8--12 days in the absence of stimulation.[2]