Neutrophils (A, arrow), stained with monoclonal antibodies directed against human neutrophil elastase, in CF alveolar lung tissue and in normal alveolar lung tissue differ significantly (p<0.0001) in numbers. Alveolar macrophages (B, arrow), stained with monoclonal antibodies directed against CD68 receptors, in CF alveolar lung tissue and in normal alveolar lung tissue differ significantly (p<0.0001) in numbers with regard to cells in septa (black bars) and intraluminally (white bars). T lymphocytes (C, arrow), stained with monoclonal antibodies directed against CD3, in CF alveolar lung tissue and in normal alveolar lung tissue differ significantly (p<0.0001) in numbers.