Correlation between eosinophilia induced by CD4(+) T cells and bronchial hyper-responsiveness

The relationship between CD4(+) T cell-mediated airway eosinophilic inflamm ation and bronchial hyper-responsiveness (BHR) was investigated. Ovalbumin- reactive T(h)o clones were adoptively transferred to unprimed BALB/c mice a nd then the mice were challenged by inhalation of the relevant antigen, Upo n antigen provocation, infused Th clones infiltrated into the airways, foll owed by the accumulation and degranulation of eosinophils, goblet cell hype rplasia, edema and increase in bronchial responsiveness to acetylcholine. T ransfer of several clones that differed in the levels of IL-5 production re vealed that the magnitude of in vivo eosinophilia strongly correlated with the IL-5-producing capacity of the infused T-h clones. Administration of an ti-IL-5 mAb almost completely suppressed antigen-induced eosinophilic infla mmation and BHR, Administration of anti-IL-4 mAb or anti-IFN-gamma mAb enha nced the eosinophilia and BHR, whereas anti-IL-2 mAb did not affect them, T he number of accumulated eosinophils significantly correlated with the inte nsity of BHR, Our present results clearly demonstrated that CD4(+) T cells induced BHR as a result of eosinophilic inflammation: IL-5 totally regulate d both responses.