Background: Cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 alpha, IL-6 and granulocyte macrophage-colony stimulating factor (GM-CSF) are able to potentiate allergic inflammation and seem to be implicated in the development of the late allergic reaction.
Methods: To study the time course of cytokine production, sequential lavages were performed after nasal allergen challenge. Thirteen patients with allergic rhinitis and four healthy subjects were exposed to grass pollen (n = 6 and n = 2, respectively) or dust mite allergen (n = 7 and n = 2, respectively).
Results: Among the patients with allergic rhinitis, a single early response (single responders) developed in four, eight exhibited a dual response (dual responders) and one patient as well as the four healthy subjects did not respond. In addition to the measurement of IL-1 alpha, IL-6, TNF-alpha and GM-CSF concentrations by ELISA, the release of histamine, tryptase, and eosinophil cationic protein was also evaluated by radioimmunoassay performed on nasal lavage fluids. Concerning mediator levels in nasal lavage fluid, neither histamine release nor cytokine elevation were noted in healthy subjects. As previously described, histamine, tryptase and eosinophil cationic protein were released in single and dual responders. Concerning cytokines, TNF-alpha was undetectable in the majority of nasal lavages and an increase in GM-CSF concentration was occasionally observed whatever the type of response. In contrast, an increase in IL-1 alpha and IL-6 levels was observed for dual responders during the early period (12.6 +/- 3 and 9.2 +/- 2 pg/ml, respectively; p < 0.01 in both cases) and at a higher level during the late period (14.5 +/- 4, p not significant and 16.7 +/- 8 pg/ml, respectively; p < 0.01) when compared with baseline values (7.2 +/- 2.2 and 2 +/- 0.7 pg/ml, respectively). For single responders IL-1 alpha and IL-6 secretion was detected mainly during the early period.
Conclusion: These data suggest a role for IL-1 alpha in the induction and perennisation of the inflammatory reaction in allergic rhinitis, whereas the role of IL-6 remains to be investigated.