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Histamine has two basic centres, namely the aliphatic amino group and whichever nitrogen atom of the imidazole ring does not already have a proton. Under physiological conditions, the aliphatic amino group (having a pK a around 9.4) will be protonated, whereas the second nitrogen of the imidazole ring (pK a ≈ 5.8) will not be protonated. [11]
The manifestations of histamine intolerance are usually systemic, affecting the entire body; still, these symptoms are often sporadic and non-specific. [5] [6] [7] The onset of symptoms is usually shortly (within a few hours) after specific food or drink consumption, and subsequent remission usually happens in 4-8 weeks of dieting, [8] that is excluding food that causes the onset of symptoms.
Mast cell activation syndrome (MCAS) is a term referring to one of two types of mast cell activation disorder (MCAD); the other type is idiopathic MCAD. [1] MCAS is an immunological condition in which mast cells, a type of white blood cell, inappropriately and excessively release chemical mediators, such as histamine, resulting in a range of chronic symptoms, sometimes including anaphylaxis or ...
Mast cells serve the same general functions in the body and central nervous system, such as effecting or regulating allergic responses, innate and adaptive immunity, autoimmunity, and inflammation. [4] [18] Across systems, mast cells serve as the main effector cell through which pathogens can affect the gut–brain axis. [19] [20]
They play an important role in the immune defence against bacteria and parasites. By releasing chemical "alarms" such as histamine, mast cells attract other key players of the immune defense system to areas of the body where they are needed. [citation needed] Mast cells seem to have other roles as well.
Depending on the chemical nature of the antigens, blood types have different levels of hypersensitivity; for instance, A and B are more antigenic than other antigens. [10] Type II hypersensitivity. Damage can be accomplished via three different mechanisms: [10] Antibody binding to cell surface receptors and altering its activity
This immune "relaxation" is incorporated throughout the immune system, decreasing immune responses against harmless allergens, gut flora, and the body itself. [9] Importance of T helper cells in an immune response: T helper cells recognize antigens from antigen-presenting cells (APCs) and then release cytokines and activate other immune cells ...
[1] [2] Histamine is a neurotransmitter involved in various physiological processes. There are four main types of histamine receptors: H1, H2, H3, and H4. H1 receptors are linked to allergic responses, H2 to gastric acid regulation, H3 to neurotransmitter release modulation, and H4 to immune system function. There are four known histamine ...