When the CF patients were considered as a single population, a highly significant positive correlation was observed between pulmonary function (measured as forced expiratory volume in one second, FEV1) and IFN-γ production by PBMCs in response to PHA (Fig. 2A) (IFN-γ vs. FEV1 (L): r = 0.5809, p = 0.0019; IFN-γ vs. % predicted FEV1: r = 0.5138, p = 0.0061). The gene discussed is IFNG; the disease is cystic fibrosis.