Late asthmatic reactions provoked by intradermal injection of T-cell peptide epitopes are not associated with bronchial mucosal infiltration of eosinophils or T(H)2-type cells or with elevated concentrations of histamine or eicosanoids in bronchoalveolar fluid

Background: Isolated late asthmatic reactions can be provoked by intraderma l challenge of allergen-derived T-cell peptide epitopes. Objective: The pur pose of this study was to determine whether the isolated LAR is associated with the local accumulation of inflammatory cells, the expression of T(H)2 cytokines, and the production of pharmacologic mediators. Methods: A randomized, placebo-controlled, crossover study design was used. The investigation involved bronchial and skin biopsies and bronchoalveolar lavage (BAL) fluids from 8 cat-allergic subjects who developed significant late asthmatic reactions 6 hours after intradermal injection of Fel d I ch ain 1-derived peptides (FC1Ps). Results: Immunostaining of bronchial biopsy specimens showed no changes in the numbers of eosinophils, neutrophils, basophils, mast cells, CD3(+), CD4 (+) or CD8(+) T cells, CD25 cells or macrophages, or cells mRNA(+) for IL-4 , IL-5, or IL-13 when the FC1P day was compared with the diluent control da y. There were also no significant differences in eosinophil numbers, either in BAL fluids or in peripheral blood after FC1P challenge. Furthermore, th ere were no significant alterations in the concentrations of histamine, his tamine-releasing factors, or eicosanoids (LTC4/D-4/E-4, PGD(2), PGE(2), TXB 2, PGF(2 alpha)) in BAL fluids. FC1Ps induced a significant (P < .05) eleva tion in CD8(+) cells in the skin and an unexpected decrease in IL-5 in BAL fluids (P = .043). Conclusion: Part of the asthma process might involve Tcell-dependent airway narrowing with no requirement for IgE, mast cells, or infiltrating inflamm atory cells.