GFP⁺, but not GFP⁻, cells express enzymatically active lysozyme P.

Cells (> 95% alveolar macrophages) from BAL of 15 lysozyme M–deficient mice were pooled and sorted by FACS based on the presence or absence of GFP. GFP expression was confirmed by epifluorescence microscopy (panel A, GFP⁺ cells; panel C, GFP⁻cells). By immunostaining with antimouse lysozyme antibody, only GFP⁺ cells (B), not GFP⁻ cells (D), expressed lysozyme, and only the GFP⁺ fraction contained enzymatically active lysozyme as determined by lysoplate analysis (E).