Pollen Grains Induce a Rapid and Biphasic Eczematous Immune Response in Atopic Eczema Patients

Abstract

Eyerich K, Huss-Marp J, Darsow U, et al. Int Arch Allergy Immunol. 2008;145(3):213–223 PURPOSE OF THE STUDY. To investigate the relationship between eczematous reactions in subjects with immunoglobulin E–mediated allergy to pollen grains. STUDY POPULATION. Two populations were evaluated: one population included subjects with atopic eczema who were sensitized to grass or birch pollen and who had a positive atopy patch test, and the second population included subjects without atopic eczema or atopy but who had a positive atopy patch test to nickel. In addition, as control populations, healthy volunteers and atopic subjects with eczema and sensitization to grass or birch but without a positive atopy patch test were included. METHODS. Atopy patch tests with native pollen grains were performed to delineate the effect of native pollen grains on human skin of healthy and atopic individuals. A nickel patch test served as an established model of contact dermatitis. Skin-site samples were taken for biopsy 6 to 96 hours after allergen application and investigated immunohistochemically. RESULTS. Histology of positive patch tests showed an influx of mononuclear cells (predominantly CD4+, CD25+, and CD45RO+). This influx was detected earlier in the pollen patch-test reactions compared with the immune response to nickel. A biphasic cytokine response could be detected in skin samples from the pollen patch test: interleukin 5 dominated in the early phase, and interferon γ dominated in the late phase. The nickel patch test was continuously dominated by interferon γ. CONCLUSIONS. Pollen grains induce eczematous reactions in susceptible individuals. This reaction seems clinically and immunohistochemically similar to the contact hypersensitivity reaction to nickel but follows a faster kinetic and a biphasic course: T-helper 2 and immunoglobulin E in the early (24-hour) phase and T-helper 1 predominance in the late (96-hour) phase. REVIEWER COMMENTS. This article highlights the importance of understanding that type 1 allergy-inducing antigens such as pollens can exacerbate atopic eczema in susceptible individuals. Physicians should remember to discuss this with their atopic patients before the start of pollen season.