Methods to isolate and culture human monocyte-derived macrophages and alveolar macrophages are described. Monocytes are obtained from buffy-coat preparations by Ficoll density gradient centrifugation, followed by adhesion-mediated purification on tissue culture or gelatin-coated plastic. The monocytes differentiate into macrophages in vitro by culturing in medium containing autologous human fibrin-depleted plasma. Alveolar macrophages can be purified from bronchoalveolar fluid samples by adhesion to tissue culture plastic. If resected lung tissue is available, alveolar macrophages can be obtained by mechanically disrupting the lung parenchyma, followed by adhesion-mediated purification.