Eosinophil granulocytes, commonly referred to as eosinophils (or less commonly as acidophils), are white blood cells that are responsible for combating infection by parasites in the body. They also have a rather diverse array of other functions, impacting multiple areas of immunology including allergy and asthma.
Eosinophils persist in the circulation for 6-12 hours, and can survive in tissue for an additional 2-3 days in the absence of stimulation. Eosinophils make up about 1-5% of the all white blood cells, and are about 10-12 micrometers in size.
Eosinophils are found naturally in the thymus (cortico-medullary junction and medulla), lower gastrointestinal track, ovary during phases of the cycle, uterus, spleen, and lymph nodes. They are not found naturally in the lung, skin, or other organs. The presence of eosinohils in the lung, skin, esophogus, or internal organs is associated with a disease process.
BMK-13
can serve as a useful pan-eosinophil marker 
				in tissue sections since it appears to stain most eosinophils.
				
				PMID: 1373987
CD9
involved in the adhesion of eosinophils to 
				fibronectin.
				
				PMID: 10704064
seem to detect activated eosinophils in the 
				circulation.
				
				PMID: 8904997
CD44 and CD69
represent different types of cell-surface 
				activation markers for human eosinophils.
				
				PMID: 9618391
CD69
a useful marker for activated eosinophils at 
				inflammatory sites.
				
				PMID: 1500624
ECP (Eosinophil Cationic Protein, EG1/EG2)
released by eosinophils, is a marker of 
				eosinophil activity.
				
				PMID: 17203813
a marker of eosinophilic activity and 
				degranulation that correlates with the severity of bronchial 
				asthma.
				
				PMID: 15719624
a serological marker of disease activity in 
				childhood bronchial asthma.
				
				PMID: 11338688
a marker of eosinophilic inflammation in 
				asthma.
				
				PMID: 9515598
EDN (eosinophil derived neurotoxin)
a catalytically proficient member of the 
				pancreatic ribonuclease superfamily secreted along with other 
				eosinophil granule proteins during innate host defense responses 
				and various eosinophil-related inflammatory and allergic 
				diseases.
				
				PMID: 16401072
one of the four basic proteins stored in 
				specific eosinophil granules, can also be detected at the 
				surface of granulocytes.
				
				PMID: 12606041
a rapidly evolving secretory protein derived 
				from eosinophilic leukocytes.
				
				PMID: 9826755
Eosinophil Peroxidase (EPO)
a simple specific marker for detecting 
				eosinophils in bronchoalveolar lavage fluid.
				
				PMID: 8437132
a unique component of eosinophils, is a 
				useful marker for the identification of eosinophils in sputum 
				and bronchoalveolar lavage fluid.
				
				PMID: 11978925
Eosinophil Protein-X (EPX)
Eosinophil activation marker.
				
				PMID: 8721862
one of the cationic proteins found in the 
				granules of the human eosinophilic granulocytes.
				
				PMID: 1865126
IL-5
eosinophil activation marker.
				
				PMID: 10714084
LA Antigen
a differentiation marker on human eosinophils.
				
				PMID: 6992887
MBP1/MBP2 (major basic protein)
MBP1 is more abundant than MBP2 in lysates of 
				eosinophils and their granules, as judged by immunoassay and 
				Western blotting. By immunofluorescence, MBP1 is present in 
				eosinophils, basophils, and a human mast cell line (HMC1), 
				whereas MBP2 is only detected in eosinophils. Neither MBP1 nor 
				MBP2 could be detected in any other peripheral blood leukocyte. 
				MBP2 is present only in eosinophils and that it may be a useful 
				biomarker for eosinophil-associated diseases.
				
				PMID: 17082653
Other Eosinophil Markers
A photoreactive fluorescent marker for 
				identifying eosinophils and their cytoplasmic granules in 
				tissues.
				
				PMID: 12533534
Systemic activation of basophils and 
				eosinophils: markers and consequences.
				
				PMID: 11080745
Surface markers of human eosinophils.
				
				PMID: 974267
3-Bromotyrosine and 3,5-dibromotyrosine are 
				major products of protein oxidation by eosinophil peroxidase: 
				potential markers for eosinophil-dependent tissue injury in 
				vivo.
				
				PMID: 10090740
Eosinophil granule proteins (MBP, ECP, EPX/EDN, EPO)--a possible process of eosinophil activation and degranulation. PMID: 8492433