Basophils

White Blood Cells. White blood cells, or leukocytes, have varying function and morphology. Mononuclear leukocytes include lymphocyte B and T-ceUs, monocytes, and progenitor cells. Polynuclear granulocytes include neutrophils, basophils, and eosinophils. The most important groups in cell separation are lymphocytes, monocytes, and granulocytes. 

Fig. 2. Mass density distribution of blood components A, platelets B, monocytes C, lymphocytes D, basophils E, neutrophils F, erythrocytes and G,...

Synthesis. Histamine [51-45-6] 2-(4-imidazolyl)ethylarnine (1) is formed by decarboxylation of histidine by the enzyme L-histidine decarboxylase (Fig. 1). Most histamine is stored preformed in cytoplasmic granules of mast cells and basophils. In humans mast cells are found in the loose connective tissue of all organs, especially around blood and lymphatic vessels and nerves. These cells are most abundant in the organs expressing allergic diseases the skin, respiratory tract, and gastrointestinal tract. 

Histamine in the Blood. After its release, histamine diffuses rapidly into the blood stream and surrounding tissues (12). Histamine appears in blood within 2.5 min after its release, peaks at 5 min, and returns to baseline levels by 15 to 30 min. In humans, the diurnal mean of plasma histamine levels is 0.13 ng/g. In urine, elevations of histamine or metaboUtes are more prolonged than plasma elevations. Consequendy, abnormahties are more easily detected by urinary histamine assay. About one-half of the histamine in normal blood is in basophils, one-third in eosinophils, and one-seventh in neutrophils the remainder is distributed among all the other blood components. Increases in blood histamine levels occur in several pathological... 

Histamine AND histamine antagonists). It is formed from histidine by the enzyme L-histidine decarboxylase. In the periphery, histamine is stored ia mast cells, basophils, cells of the gastric mucosa, and epidermal cells. In the CNS, histamine is released from nerve cells and acts as a neurotransmitter. The actions of histamine ate terrninated by methylation and subsequent oxidation via the enzymes histamine-/V-methyltransferase and monoamine oxidase. 

The most serious acute Type I reaction is the generalized reaction, the anaphylactic shock. Anaphylactic shock results from a generalized release of mediators from mast cells and basophils. The clinical symptoms are manifested predominantly in... 

Basophils constitute a subgroup of circulating blood cells (leucocytes). In many aspects they resemble... 

Although mast cells and basophils probably account for >90% of stored histamine in the body, histamine is also present in platelets, enterochromaffin-like cells, endothelial cells, and neurons. Histamine can act as a neurotransmitter in the brain. Histaminergic nerves have their cell bodies within a very small area of the brain (the magnocellular nuclei of the posterior hypothalamus) but have axons in most areas of the forebrain. There is also evidence for axons projecting into the spinal (Fig. 1) cord. Finally, there is evidence that histamine synthesis can be induced in tissues undergoing rapid tissue growth and repair. In certain neonatal tissues (e.g. liver), the rate of synthesis of this unstored diffusable histamine (termed nascent histamine) is profound and may point to a role for histamine is cell proliferation. 

Type I allergic reactions are inappropriate immune responses to an allergen with preferential synthesis of immunoglobulin E (IgE), a special antibody class, which binds to mast cells and basophilic granulocytes via Fee receptors. Binding of the allergen to the cell-bound IgE initiates the rapid release of allergic mediators, most prominently histamine, and the de novo synthesis of arachidonic acid metabolites and cytokines, which are responsible for the clinical symptoms. 

Syk and ZAP-70 are early intermediates in the transduction of signals from immune receptors, including the B- and T-cell recqrtors for antigen, activatory natural killer-cell receptors, the mast cell and basophil receptor for IgE, and the widely distributed receptors for the Fc portion of IgG. Immune receptors control checkpoints in lymphocyte development and serve to integrate the responses of innate and acquired immunity. 

Bartter s Syndrome Basal Activity Basal Ganglia Basement Membrane Basophils Bax... 

Histamine is a substance present in various tissues of die body, such as die heart, lungs, gastric mucosa, and skin (Pig. 36-1). The highest concentration of histamine is found in die basophil (a type of white blood cell) and mast cells diat are found near capillaries. Histamine is produced in response to injury. It acts on areas such as die vascular system and smooth muscle, producing dilatation of arterioles and an increased permeability of capillaries and venules. Dilatation of die arterioles results in localized redness. An increase in die permeability of... 

The most serious adverse reaction associated with these drugs is agranulocytosis (decrease in the number of white blood cells [eg, neutrophils, basophils, and eosinophils]). Reactions observed with agranulocytosis include hay fever, sore throat, skin rash, fever, or headache Other major reactions include exfoliative dermatitis, granulocytopenia, aplastic anemia, hypoprothrombinemia, and hepatitis. Minor reactions, such as nausea, vomiting, and paresthesias, also may be seen. 

Muscle biopsy with full histochemical and ultrastructural investigation is necessary for the confirmation of a diagnosis of IBM. The inclusions which are the hallmark of this disorder are to be found in three locations (a) basophilic granular inclusions are found at the periphery of vacuoles within the cytoplasm of muscle fibers (b) eosinophilic hyaline inclusions are also found in the cytoplasm but are not associated with vacuoles and (c) intranuclear inclusions consisting of aggregates of filamentous microtubules are found in a variable percentage of muscle nuclei. Inclusions of the first two types are visible at light microscope level, whereas the third type is detectable at the electron microscope level only. Ultrastructural... 

There are also other immimological mechanisms, especially via IgG or IgM antibodies with immune complex formation, which can lead to similar clinical conditions [20, 34, 42] as has been shown in dextran anaphylaxis (table 1). Triggering of mast cells and basophils leads to release of various vasoactive mediators, among which histamine was the first recognized in 1908 (fig. 3,4) [6]. 

Mast cell or basophil leukemia Carcinoid syndrome Thyroid carcinoma Pheochromocytoma... 

Fig. 3. Th2 cells provide cytokines such as IL-4, IL-5, IL-9 and IL-13, which are essential for differentiation, survival and activity of basophils, mast cells and eosinophils. IL-4 and IL-13 induce IgE production from B cells. IL-5 induces eosinophils, increases eosinophil survival and reduces apoptosis. IL-9 stimulates mast cells. 

Fig. 4. Regulatory T-cell functions suppression of DCs that support the generation of effector T cells suppression of ThI, Th2, and ThI 7 cells suppression of allergen-specific IgE and induction of lgG4, IgA, or both suppression of mast cells, basophils, and eosinophils interaction with resident tissue cells and remodeling, and suppression of effectorT-cell migration to tissues. 

Shim JY, Kim BS, Cho SH, Min KU, Hong SJ Allergen-specific conventional immunotherapy decreases immunoglobulin E-mediated basophil histamine releasability. Clin Exp Allergy 2003 33 52-57. 

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