The variability of type I hypersensitivity reactions: the importance of mood

Immediate (Type I) hypersensitivity skin reactions to allergens or antigens have been used as immune measures that may be subject to intentional modulation. In preliminary experiments using hypnosis we encountered unacceptably large, uncontrollable variability. A method was subsequently devised in which serial, five-fold dilutions of allergen or histamine were administered to the subject's forearm and reactions were recorded photographically on slide film. Areas were determined by computer-assisted image analysis. Seven healthy volunteers were tested for eight sessions (testing included mood scales, blood pressure, pulse and skin temperature). Mean wheal size and titration gradient data from allergen reactions correlated strongly with the psychological factor of liveliness but not stress, although no manipulation of mood was involved. A stepwise regression analysis accounted for 61% of the variance of the allergen mean wheal data, and 31% was from the liveliness factor alone. Thus, the more lively the subject felt, the smaller was the allergic response.