Blackwell Publishing Journal Backfiles 1879-2005
Background: This study was designed to examine the effect of passive sensitization (PS) on human bronchial mast cells. PS with asthmatic serum induces a hyper-responsiveness to nonspecific agonists, and immunoglobulin (Ig)E binding mainly on mast cells.Methods: Bronchi dissected out from 19 lung specimens were incubated in normal or asthmatic serum. Immunohistochemistry was performed using monoclonal antibodies (MoAbs) directed against tryptase, chymase, or c-kit. Mast cells were classified as fully granulated (type I), partly (type II) or largely degranulated (type III). Tryptase was measured in supernatant using ELISA. Contractile response was recorded in a separated set of experiments using an organ bath system.Results: PS decreased both tryptase positive cells (47.9 ± 10.0 vs. 26.7 ± 4.8 cell/mm2, P = 0.003) and chymase positive cells (26.1 ± 3.3 vs. 14.9 ± 1.8 cell/mm2, P = 0.01), but did not alter the number of c-kit positive cell. PS decreased the proportion of type I (55.4 vs. 28.9%, P 〈 0.0001) and, concomitantly increased that of types II (23.2 vs. 41.0%, P 〈 0.0001) and III (21.4 vs. 30.1%, P = 0.04). Following PS, tryptase concentration significantly increased and the magnitude of histamine response, was correlated with the amount of type II mast cells.Conclusion: PS of human isolated bronchi induces a mast cell degranulation related to in vitro hyper-responsiveness, along with a tryptase release.
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