Distribution of plexin A proteins in antigen-presenting cells, BAL fluid, and lung tissue derived from CBD patients. (A) Western blot analysis of cell extracts from the mouse fibroblast cell lines (DP8302 and DP2.21) and EBV-transformed B cells from CBD patient 1332 and BAL fluid from two representative CBD patients is shown. Anti-plexin antibodies cross-react to mouse and human plexin A2 and A4. BAL fluid samples were concentrated 300-fold and resolved on a 7.5% polyacrylamide gel. Results are representative of a minimum of three independent experiments for cell extracts and BAL fluids. (B and C) Immunofluorescence staining of plexin A2 (red) and cell nuclei (blue) in mouse cerebellum (B) and transbronchial lung biopsy tissue from a CBD patient (C) is shown. An enlarged view of the area within the white box in C showing plexin A2 expression in bronchial epithelial cells is shown in the right panel. Results are representative of the three transbronchial lung biopsy specimens analyzed.