Of self‐lipids, CD1‐restricted T cells, and contact sensitization

Abstract

Contact hypersensitivity (CHS) in rodents and

The Global Rise and the Complexity of Sesame Allergy: Prime Time to Regulate Sesame in the United States of America?

“…Lipid allergens in general are small hydrophobic chemicals present in plant oils (sesame oil, cashew nutshell oil, poison ivy, poison oak, poison sumac) and cosmetics such as fragrance, toothpaste, and hair dyes (e.g., balsam of Peru, urushiol of poison ivy, farnesol, benzyl benzoate, benzyl cinnamate) [86][87][88][89][90][91]. The mechanisms through which they trigger allergic reactions have been deciphered for some of the lipid allergens, but not for sesame lipid allergens [86][87][88][89][90][91]. Furthermore, some of these lipid allergens show structures similar to that of sesame lipid allergens.…”

“…Entry of lipid allergens into the body of susceptible subjects leads to their uptake by the APCs, such as Langerhans cells and presentation to specific naïve T cells to initiate their proliferation and differentiation into effector and memory T cells [86][87][88][89][90][91] (Figure 3). There are two models to explain specifics on how APCs are able to do this.…”

“…The first model suggests that lipid allergens, which are considered as haptens because of their very small sizes of <500 Daltons, form covalent bonds to host proteins, resulting in an immunogenic hapten-carrier complex molecule that is then presented by the APCs in the context of MHC class II molecules to T cells that get activated [86]. The second, and most recent, model suggests that lipids allergens can also directly bind to CD1a molecule, a non-classical MHC molecule expressed by the Langerhans cells (a type of APC) in the skin, by displaying the self-lipids normally bound to the CD1a inside its molecular cleft or hole [87][88][89][90][91]. This results in the presentation of lipid allergens to which T cell reactions are initiated, resulting in the formation of specific effector and memory T cells.…”

“…Re-exposure of a previously sensitized subject to the same lipid allergens results in their entry and presentation of by the APCs to the pre-formed allergen specific effector and memory T cells [86][87][88][89][90][91] (Figure 3). This results in their activation, proliferation, and release of cytokines and chemokines into the local tissues and eventually into the blood.…”