Allergy Skin Testing
Pudupakkam K Vedanthan, Harold S Nelson, Shripad N Agashe, PA Mahesh, Rohit Katial in Textbook of Allergy for the Clinician, 2021
AST is a bio assay to determine the presence of specific IgE antibodies on the surface of mast cells. A positive AST is elicited when a specific allergen is introduced into the skin and a wheal and flare reaction develop over a period of 15–20 minutes. ‘Sensitization’ is an immunologic term; it does not mean the person is ‘allergic’ which indicates the individual is not only sensitized, but also has symptoms on exposure to the allergen. Hence AST determines sensitization and confirms allergy based upon the clinical presentation. The mechanism of Type 1 Hypersensitivity is depicted diagrammatically in Fig. 4.1. There are two phases in allergic reaction:1. Sensitization,2. Re-exposure.
Gender and Age Influence on Sensitive Skin
Golara Honari, Rosa M. Andersen, Howard Maibach in Sensitive Skin Syndrome, 2017
Sensitization requires, opposite to irritation, an immune response and therefore immune competence to carry out a skin response to allergens—allergic dermatitis. It is difficult to explore if there is any difference in inherent immune competence or susceptibility comparing gender or various age groups. The big challenge is to separate gender-/age-related inherent susceptibility from gender-/age-related patterns of exposures/behavior. The only way to truly assess allergic sensitivity is thus to evaluate the induction of allergic contact sensitization in previously naive subjects, which nowadays, due to ethical aspects, is not conducted. This leaves us with difficult interpretations of retrospective studies of patch-testing cohorts and older studies investigating naive cohorts. A retrospective study from 1986 of 1873 persons who underwent patch-testing revealed significant increased sensitization in the elderly (
Allergy: Basic Mechanisms and Tests
John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie in Basic Sciences Endocrine Surgery Rhinology, 2018
Allergy is defined as a hypersensitivity reaction initiated by specific immunologic mechanisms. By a specific definition, it describes objectively reproducible symptoms or signs initiated by an exposure to a defined stimulus at a dose tolerated by normal persons. Hypersensitivity is an altered immune response to an antigen that can cause damage. Immunologically four types of hypersensitivity reactions are generally recognized (Table 14.1). An allergen is an antigen (usually protein) that causes allergic diseases. Allergic airway diseases including rhinitis are due to inhaled allergens (Table 14.2). Atopy is a tendency to become sensitized and produce allergen-specific immunoglobulin E (sIgE) in response to ordinary exposures to allergens. Clinically this is demonstrated by positive skin prick tests and/or increased serum sIgE concentration to one or more allergens. Not all sensitized individuals are symptomatic. Therefore allergy is a disease manifestation of sensitization. We will consider the basic mechanism of allergy initially in which an individual is predisposed to allergy by sensitization to allergens. Then we will consider the immunological process involved in some allergic diseases and the effect of treatment including current understanding of specific allergen immunotherapy. Finally the principles of diagnostic tests will be considered.
Alcohol use disorder and risk of sensitization to environmental allergens in Sub-Continental Asian Indian males
Published in Journal of Addictive Diseases, 2018
Yashwant Kumar, PVM Laxmi, Ranjana Walker Minz, Arnab Pal
Alcohol is known to cause elevation of serum total IgE (tIgE). Whether it can predispose to allergic disorders, however, is not clear. To assess whether alcohol can cause sensitization to allergens, we analyzed 100 individuals with alcohol use disorder (AUD) and 50 matched healthy controls. Serum tIgE and specific IgE against environmental allergens were measured. We found 93% of individuals with AUD had raised tIgE compared to only 48% of healthy controls (p
The sensitization potential of sunscreen after ablative fractional skin resurfacing using modified human repeated insult patch test
Published in Journal of Dermatological Treatment, 2015
Waranya Boonchai, Angkana Sathaworawong, Chanisada Wongpraparut, Rungsima Wanitphakdeedecha
Background: Ablative fractional skin resurfacing has become popular and proven to be useful in treating scars, photoaging and wrinkles. Although post-inflammatory hyperpigmentation (PIH) is the most common complication especially in dark-skinned patients like Asian. Several modalities have been used to overcome the PIH. Objective: To determine the sensitization potential of sunscreen applied immediately after ablative fractional skin resurfacing. Material and methods: Sixty volunteers were recruited. Of these 30 subjects were from previous ablative fractional skin resurfacing study who applied broad-spectrum sunscreen containing anti-inflammatory agent starting on the first day after resurfacing and another 30 non-resurfacing subjects had applied the same sunscreen on the intact skin. All subjects were patch/photopatch tested for sensitization study by using modified human repeated insult patch test (HRIPT). Results: There were significantly higher sensitization rate of UV-filter, octocrylene and the sunscreen in resurfacing group than in non-resurfacing group. Conclusion: Early application of sunscreen after ablative fractional skin resurfacing has increased the incidence of sensitization potential of sunscreen. The sunscreen is recommended to start using from D3 after fractional ablative skin resurfacing to ensure the complete recovery of skin barrier and minimize the risk of sensitization.
Computational approaches for skin sensitization prediction
Published in Critical Reviews in Toxicology, 2018
Anke Wilm, Jochen Kühnl, Johannes Kirchmair
Drugs, cosmetics, preservatives, fragrances, pesticides, metals, and other chemicals can cause skin sensitization. The ability to predict the skin sensitization potential and potency of substances is therefore of enormous importance to a host of different industries, to customers’ and workers’ safety. Animal experiments have been the preferred testing method for most risk assessment and regulatory purposes but considerable efforts to replace them with non-animal models and in silico models are ongoing. This review provides a comprehensive overview of the computational approaches and models that have been developed for skin sensitization prediction over the last 10 years. The scope and limitations of rule-based approaches, read-across, linear and nonlinear (quantitative) structure–activity relationship ((Q)SAR) modeling, hybrid or combined approaches, and models integrating computational methods with experimental results are discussed followed by examples of relevant models. Emphasis is placed on models that are accessible to the scientific community, and on model validation. A dedicated section reports on comparative performance assessments of various approaches and models. The review also provides a concise overview of relevant data sources on skin sensitization.