In Reply.—
We appreciate Bourke's comments on our article,1 and we fully agree with his concept that hypersensitivity pneumonitis is a complex clinical syndrome and that subtle, but important, differences between populations may exist in manifestation of the disease.In Mexico, we mainly deal with the chronic form of pigeon breeder's disease that is related to domestic, lowgrade, constant, and prolonged exposure to avian antigens.2 What we have observed in the last years is that chronic pigeon breeder's disease may follow different clinical courses, ie, some patients can recover, others remain with clinical and/or functional abnormalities, and in others the condition becomes worse and interstitial fibrosis develops. Interestingly, despite avoiding exposure and initiating a well-controlled therapy, progression to pulmonary fibrosis has appeared in about 30% to 40% of our patients.2,3 In this context, the linkage between inflammation and fibrosis is one of the most fascinating and