Since we observed the development of prolonged airway inflammation only in a model in which Fas-deficient T cells are transferred into a lymphopenic host, we sought to test whether induction of lymphopenia in the intact Fasfl/fllck-cre or B6.LPR mice would induce the prolonged eosinophilia as previously found in the adoptive transfer model. The gene discussed is FAS; the disease is lymphopenia.