Eosinophil

From Anvita Health Wiki

Contents 1 Function 2 Pathology 3 Biochemistry 4 Physiology 5 Laboratory 6 More General Terms 7 Additional Terms 8 References

Function

• eosinophils are involved in allergic responses & are the 1st line of defense against helminths
• eosinophils are phagocytes

• phagocytosis of foreign particles
• phagocytosis of antigen- antibody complexes

• eosinophic granules contain inflammatory mediators

• larger granules

• major basic protein
• acid hydrolases
• eosinophil peroxidase
• phospholipase
• eosinophil cationic protein ( ribonuclease-3)
• eosinophil-derived neurotoxin ( ribonuclease-2)
• eosinophil protein X

• smaller granules

• arylsulfatase
• acid phosphatase

• eosinophils also produce:

• reactive oxygen species
• LTC4
• platelet-activating factor
• cytokines

• eosinophils dampen inflammatory responses [3]

Pathology

• Charcot-Leyden crystals (a product of eosinophil degeneration) may be seen in areas of eosinophil accumulation
• inflammatory mediators of eosinophils are toxic to respiratory epithelial cells & result in shedding of these cells
• Creola bodies are clumps of sloughed respiratory epithelium in sputum of asthmatic patients

Biochemistry

• eosinophils express the chemokine receptor CCR3

Physiology

• derived from common granulocyte-monocyte stem cell in bone marrow -> committed eosinophilic progenitor cell
• 3 growth factors produced by lymphocytes affect eosinophil maturation ( GM-CSF, IL2 & IL5)
• IL5 promotes terminal maturation & functional activation & prevents apoptosis of eosinophils
• 1/2 life in peripheral blood is ~ 18 hours after which they migrate into tissues where they survive for at least 6 days
• adrenocortical steroids expedite eosinophil migration from blood into tissues
• neutrophils in tissues are ~100 X more abundant than in blood
• within tissues they are found at epithelial barriers to the outside word, i.e. lung & respiratory tract, GI tract, skin
• eosinophil chemotactic factors:

• leukotrienes
• platelet-activating factor ( PAF)
• cytokines:

• interleukin-5 (IL-5)
• monocyte chemotactic protein
• RANTES

• other factors in eosinophil recruitment

• induction of VCAM-1 by endothelial cells b ) VCAM-1 binding of VLA-4 on eosinophils

Laboratory

• component of complete blood count with differential
• normal eosinophil count is 150-300/ uL, & 1-4% of circulating WBC

More General Terms

• granulocyte

Additional Terms

• eosinophil peroxidase (EPX, EPER, EPO, EPP)
• eosinophilia
• eosinophils in blood
• eosinophils in urine
• eosinophiluria
• leukotriene C4

References

1. Internal Medicine, Stein et al (eds), Little Brow & Co, Boston 1983, pg 1137
2. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
3. Henry's Clinical Diagnosis & Management by Laboratory Methods, 21st edition, McPherson RA & Pincus MR (es), W.B. Saunders Co., Philadelphia, PA. 2007, page 495

eosinophil