Research About EGID
What is an Eosinophil?
The eosinophil is a specialized cell of the immune system. This pro-inflammatory white blood cell generally has a nucleus with two lobes (bilobed) and cytoplasm filled with approximately 200 large granules containing enzymes and proteins with different (known and unknown) functions.
Eosinophils are formed exclusively in the bone marrow, where they spend about 8 days in the process of maturation before moving into the blood vessels. They travel through the vessels for 8 to 12 hours before they finally arrive at destination tissues, where they remain for 1 to 2 weeks. Interleukin 5 (IL-5) appears to be the major growth factor for this type of cell.
The functions of the eosinophil are varied, some of which are very similar to other white blood cells. They are implicated in numerous inflammatory processes, especially allergic disorders. In addition, eosinophils may have a physiological role in organ formation (e. g. postgestational mammary gland development).
Eosinophilic functions include moving to inflamed areas, trapping substances, killing cells, antiparasitic and bactericidal activity, participating in immediate allergic reactions, and modulating inflammatory responses.
Eosinophils can be either helpful or harmful. At one extreme, such as in the illness erythema toxicum, eosinophils play the role of a beneficial modulatory element or an innocent bystander. At the other extreme, represented by conditions like Loeffler’s disease and idiopathic hypereosinophilic syndrome, eosinophils are linked with permanent pathologic changes.
What is an Eosinophilic Disorder?
Eosinophils are a normal cellular component of the blood and also of certain tissues, including spleen, lymph nodes, thymus, and the submucosal areas of the gastrointestinal, respiratory, and genitourinary tracts. Counts of 0 to 450 eosinophils per cubic millimeter of blood are considered within normal limits. Eosinophilic disorders occur when eosinophils are found in above-normal amounts in various parts of the body.
When the body wants to attack a substance, such as an allergy-triggering food or airborne allergen, eosinophils respond by moving into the area and releasing a variety of toxins. However, when the body produces too many eosinophils, they can cause chronic inflammation resulting in tissue damage. Eosinophilic disorders are diagnosed according to the location where the levels of eosinophils are elevated:
Eosinophilic esophagitis (esophagus)
Eosinophilic gastritis (stomach)
Eosinophilic enteritis (small intestine)
Eosinophilic colitis (large intestine)
Hypereosinophilic syndrome (blood and any organ)
There are many disorders where eosinophils have been found elevated in the blood or different tissues. General categories of disease, each with examples of those that have increased levels of eosinophils, range from allergic disorders to endocrine disorders.
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Range of Disorders
Allergic disorders are classically characterized by the presence of eosinophils. Allergic rhinoconjunctivitis (hay fever) has increased levels of eosinophils in the nasal mucosa. Asthma, after an exacerbation, shows increased numbers of eosinophils in the lung.
Any drug/medicine has the potential to cause a reaction. Some of these reactions are allergic in nature, and eosinophils might be elevated in blood or in tissues where the drug is concentrated.
Parasitic infections (helminthiasis − worms), fungal infections, and some other types of infections are associated with increased numbers of eosinophils.
Hematologic disorders with increased levels of eosinophils include hypereosinophilic syndrome, leukemias, lymphomas, tumors, mastocytosis, and atheroembolic disease.
Immunologic Disorders and Reactions
Hyper-IgE syndrome, Omenn’s syndrome, thymomas, and transplant rejections are only a few types of conditions with increased numbers of eosinophils.
Hypoadrenalism has been associated with increases in the levels of eosinophils in the blood.
Specific Organ Involvement
There are certain conditions where eosinophils have been found to be increased or pathologically present.
Skin and Subcutaneous Disorders
Atopic dermatitis (eczema), bullous pemphigoid, pemphigus vulgaris, dermatitis herpetiformis, drug-induced lesions, urticaria, eosinophilic panniculitis, angioedema with eosinophilia, Kimura’s disease, Shulman’s syndrome, Well’s syndrome, eosinophilic ulcer of the oral mucosa, eosinophilic pustular folliculitis, and recurrent cutaneous necrotizing eosinophilic vasculitis.
Drug / toxin-induced eosinophilic lung disease, Loeffler’s syndrome, allergic bronchopulmonary aspergillosis, eosinophilic pneumonia, Churg-Strauss syndrome, eosinophilic granuloma, and pleural eosinophilia.
Gastroesophageal reflux, parasitic infections, fungal infections, Helicobacter pylori infections, inflammatory bowel disease (ulcerative colitis and Crohn’s disease), food allergic disorders, protein-induced enteropathy and protein-induced enterocolitis, allergic colitis, celiac disease, pemphigus vegetans (MR) and primary eosinophilic esophagitis, gastroenteritis, and colitis. Rare tumors (leiomyomatosis), connective tissue disorders, and vasculitic disorders.
Organizing chronic subdural hematoma membranes, central nervous system infections, ventriculoperitoneal shunts, and drug-induced adverse reactions.
Secondary to systemic disorders such as the hypereosinophilic syndrome or the Churg-Strauss syndrome, heart damage has been reported. Certain congenital heart conditions (septal defects, aortic stenosis) are associated with increased levels of eosinophils in the blood.
Eosinophiluria (eosinophils in the urine) is associated with infections or interstitial nephritis and eosinophilic cystitis.
Psychological Effects of Eosinophilic Disorders
Many parents have questions about the psychological effects that an eosinophilic disorder can have on their child. Here are answers, provided by the experts at the Cincinnati Center for Eosinophilic Disorders at Cincinnati Children’s, to some frequently asked questions. Expand the following categories for specific examples: