A model of allergen-driven human airway contraction: beta2 pathway dysfunction without cytokine involvement.

Background: In our previous in vitro model, allergen incubation of passively sensitized human airways reduced the response to salbutamol. However, whether cytokines play a role in this model is still unknown.

Objective: To investigate interleukin 1beta and tumor necrosis factor a expression in allergen-challenged human airways.

Methods: Nonasthmatic airways (n = 13) were passively sensitized by overnight atopic serum incubation and then challenged with allergen for 1 hour (n = 9). After repeated washouts, airways were immersed in physiologic salt solution for 6 hours and finally in formaldehyde for immunohistochemical studies. The effect of co-incubation in anti-interleukin 1beta and anti-tumor necrosis factor a specific neutralizing antibodies on salbutamol response was also studied (n = 4).

Results: No differences were found among control, sensitized, and challenged rings in the number of inflammatory cells. The percentage of basement membrane covered by epithelium was similar in the different conditions. There was a higher percentage of degranulating to total mast cells in allergen-challenged rings than in sensitized rings (P < .001). A significant correlation was observed between allergen-induced contraction and mast cell degranulation (r = 0.88; P < .001). The sensitization procedure was validated by paired allergen-induced contractions. No expression of the 2 cytokines was detectable up to 6 hours after allergen challenge, and specific neutralizing antibodies did not attenuate the impaired response to salbutamol in allergen-challenged rings.

Conclusion: These data suggest that in our in vitro model of allergic inflammation, beta2 pathway dysfunction can occur without cytokine involvement, thus supporting previous results that suggest a role for leukotrienes.