A-C: Bone marrow-derived GFP+ cells infiltrated the lung following acute bacterial pneumonia. Confocal microscopy images of the lung. Irradiated mice were transplanted with whole bone marrow from GFP+ Tg mice. After induction of pneumonia by E. coli instillation, lungs were fixed and stained for GFP with anti-GFP antibodies. A: Cryosection of the lung, which shows co-localization of signal from Texas Red-labeled antibody against GFP (red, upper left panel) with GFP signal (green, upper right panel). The lower panel is a combined image. B: Paraffin section of the lung from the same experiment. Lungs are co-stained for DNA with Propidium Iodine (Upper left panel) and stained with anti-GFP antibody and secondary FITC labeled antibody (Upper right panel). Lower left panel – tissue image in reflected light, lower right panel – combined image. C: Control staining of paraffin-sectioned lungs with isotype primary antibody, no non-specific green fluorescence can be noted, same panel description as in B. D-E: PRXV was abundantly present in cells of the bronchial epithelium of mice, and acute bacterial inflammation did not further significantly increase it. Confocal microscopy images of the cryosectioned lung, stained for PRXV with red-fluorescent secondary antibody. D: – Non-inflamed control lung (cryosection), original magnification × 40, bar is 50 microns. Note high expression of PRXV in the bronchial epithelium (blue arrow) but not in the alveoli (green arrow). E: Control staining with isotype primary antibody; no non-specific red fluorescence is present. F: GFP+ cells, which are present in high numbers in the lung following pneumonia, highly express PRXV. Cryosection of the lung, stained for PRXV with Rhodamine-labeled antibodies (red). Fluorescence intensity of the bronchial epithelium does not differ from control (Panel D). Note the presence of bright green GFP+ (or yellow due to superposition of green GFP and red PRXV signals) cells, which also highly express PRXV.