title: Application of thermography for the assessment of allergen-induced skin reactions.
abstract: OBJECTIVE
  The allergic response is commonly identified and assessed by skin testing. The usual method to quantify skin reactions is to mark wheal and erythema regions and assess the surfaces affected by the reactions; however, subjective interpretation of the outcome may cause errors. Skin thermography supplemented by a mathematical model based on the pathophysiology of heat generation was evaluated as a novel, objective, and sensitive indicator of the skin prick test result.
  
  
  METHODS
  TH measurements were performed simultaneously with routine skin prick tests for 24 patients. Eight allergens and control (histamine) were examined. Thermographic images of both forearms were acquired every 70 s from 0 to 910 s after skin prick and analyzed with the use of dedicated software. The introduction of potential allergens and histamine at sites on the skin induces a complex sequence of events known as the local inflammatory response. The crucial steps of the process have been considered in the model. In the model, the authors assumed that the reaction takes place in the thin skin layer and that histamine is the principal mediator of the allergic reaction. Histamine penetrates the skin and binds to receptors of nearby capillaries and venules. The engorged vessels are, in turn, responsible for skin redness and an increase in skin temperature.
  
  
  RESULTS
  The model parameters were determined by fitting the analytical solutions to the spatiotemporal distributions of the differences between measured and baseline temperatures. The model reproduces experimental data very well. The coefficient of determination ranged from 0.805 to 0.995. Seven model parameters were tested to find the optimal marker of the intensity and kinetics of the allergic reaction. The parameter which quantifies a release of histamine after allergen injection has appeared to be the best indicator of the allergen-induced response. The parameter correlates with the routine assessment based on wheal and erythema areas (correlation coefficient = 0.98).
  
  
  CONCLUSIONS
  It was demonstrated that the thermographic measurements supplemented by the mathematical model offer a new approach to the quantification of allergen-induced skin reactions. Despite the applied simplifications, the proposed model reflected properly the mechanism of heat generation during skin prick test. Moreover, the continuous recording of the skin temperature represents an additional possibility to investigate the mechanism of the allergic reaction.
authors: Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Cracow, Poland. ufrokita@cyf-kr.edu.pl
authors: Eugeniusz
authors: E
authors: Rokita
authors: Tomasz
authors: T
authors: Rok
authors: Grzegorz
authors: G
authors: Tatoń
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D006632:Histamine / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis* / Q000276:immunology / Q000503:physiopathology; D008875:Middle Aged; D012867:Skin / Q000276:immunology* / Q000503:physiopathology; D012881:Skin Temperature / Q000276:immunology; D013817:Thermography / Q000379:methods*; D055815:Young Adult
chemical_list: D000485:Allergens; D006632:Histamine