Cellular Infiltration in Allergic Late-Phase Reaction of the Nose: Immunohistochemical Studies

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Abstract
As with the bronchial system and the skin, the human nose may react with an immediate-phase (IPR) and late-phase reaction (LPR) upon allergen exposure. In this study we challenged intranasally 11 unselected grass-pollen-allergic patients and three normal controls with increasing allergen concentrations to provoke similar IPR symptoms in each person. A nasal symptom score and the bilateral nasal resistance were measured for 8 hours, repeated mucosal surface cell samples were performed (brush technique) before and every 2 hours after the challenge for histological and immunohistochemical investigations on cellular events during the nasal LPR. Apart from neutrophil and eosinophil infiltration, the LPR was accompanied by the migration of metachromatic cells, IgE positive cells, and macrophages/monocyte-like cells. IgE-positive cells could be identified as mast cells/basophils; from the discrepancy between the numbers of IgE- and metachromatic cell types we conclude the degranulation of these mediator cells not only during the IPR, but also during the LPR. The migration of IGE-bearing mediator cells onto the mucosal surface may represent an explanation for the increased reactivity of the organ due to repeated allergen exposure. Furthermore, the migration points to these cells as a means of transport for IgE molecules. The increase in density of macrophages/monocyte-like cells on the nasal mucosal surface during the LPR suggests an important role of these inflammatory cells in antigen processing and/or maintaining of chronic inflammatory reactions.