IgE-Mast cell mediated allergy: a sensor of food quality
“allergic sensitization triggers the formation of avoidance behavior”, food can
contain toxic noxious substances in different amounts and our bodies have ways
of directly sensing it and responding to protect itself, including extra mucous
production, nausea, vomiting, diarrhea, malabsorption, increased peristalsis. These protective responses can be in response
to our bodies sensing the toxicity via smell, taste, chemosensors in the
gut. This is a system that senses food
quality and is more general and doesn’t adapt over time.
“Type 1 allergic reactions can induce similar symptoms as already known sensors of food quality. This similarity suggested that type 1 allergic reactions may also act as a ‘food quality control system” that allows learning and behaviour adaptation.3 The great advantage of involving the immune system would be its ability to recognize a nearly infinite number of distinct substances in a very specific manner, which is an original property of the adaptive immune system.” , “early type 1 allergic reactions trigger persistent allergen-specific avoidance behavior” , mice that were deficient in IgE and/or mast cells didn’t develop avoidance behavior. “Type 1 allergic reactions promote protective antigen avoidance behaviour via IgE armed mast cells.”
“In response to allergic stimulation, cytokines from Tfh cells promote antibody class switch and antibody secretion by B cells, which yield antibodies of various isotypes, including IgE and IgG. IgE arms mast cells with an antigen-specific receptor.”, “during the early preclinical allergic response, mast cells are sufficiently activated to release leukotrienes, which triggers long-lasting allergen-specific avoidance behavior.” If the exposure to the allergen persists IgE levels may increase and it increases its affinity to the allergen and “trigger strong mast cell activation and allergic disease.”
“In the absence of IgE or mast cells, allergen ingestion is increased, eventually leading to severe immunopathology.”
“IgE production is dependent on IL-4 from T follicular helper (Tfh) cells. This cytokine is sufficient to induce low affinity IgE, which however does not induce severe allergic symptoms, while additional cytokines from Tfh13 cells, including IL-13 and IL-21, are required for the development of high affinity IgE and anaphylaxis”
“High affinity IgE-mediated mast cell activation is the major mechanism for the induction of severe type-1 allergic reactions.” “murine IgG1 (human IgG4) antibodies which are also induced by IL-4, can trigger anaphylaxis too, though only in the presence of higher amounts of antigen”
“Antibodies of the subclasses IgG2 and IgG3 are not IL-4 dependent, may not contribute to the pathology of type 1 allergic reactions, but can mediate severe inflammation via the activation of the complement system and various innate effector cells.”
“most allergic symptoms are absent in IgE deficient mice, even after forced uptake of high amounts of allergen, they still develop severe anaphylaxis, probably involving antibodies of other subclasses.”
“This work reveals a protective role of IgE-mediated mast cell activation, acting via modification of behavior.”
“even early allergic symptoms are associated with the activation of areas of the brain involved in the response to aversive stimuli.”
“the induction of allergen avoidance behavior required only mild allergic reactions mediated by IgE, which precede the development of gut allergic inflammation. Evidence was provided, that activated mast cells affect behavior through the release of cysteinyl leukotrienes and the induction of growth and differentiation factor 15 by colonic epithelial cells, eventually sensed by the nervous system.”
“early IgE-mediated allergic reaction triggers avoidance behaviour while chronic allergen ingestion results in IgE-mediated disease.”
“The ratios between the levels of allergen specific IgE and the levels of allergen specific antibodies of other subclasses, correlate better with the development of severe allergic symptoms than the levels of IgE alone.”
“This reflects the fact that antibodies of other subclasses such as IgG1 or IgA can inhibit the severe allergic reactions induced by high-affinity IgE.”
“this mechanism may also be relevant in non-allergic individuals, who nevertheless produce subclinical quantities of IgE, potentially sufficient to cause mild mast cell activation and behavioural change, but without triggering allergic pathology.”
Immune sensing of food allergens promotes avoidance
behaviour
https://www.nature.com/articles/s41586-023-06362-4
Mast cells link immune sensing to antigen-avoidance
behaviour
https://www.nature.com/articles/s41586-023-06188-0
Food allergy as a biological food quality control system
https://www.cell.com/cell/fulltext/S0092-8674(20)31677-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867420316779%3Fshowall%3Dtrue
Identification of a T follicular helper cell subset that
drives anaphylactic IgE
https://www.science.org/doi/10.1126/science.aaw6433
B-cell receptor physical properties affect relative IgG1 and
IgE responses in mouse egg allergy
https://www.mucosalimmunology.org/article/S1933-0219(22)01761-5/fulltext
T follicular helper cells
https://www.immunology.org/public-information/bitesized-immunology/cells/t-follicular-helper-cells
