Alveolar macrophages of lys M^−/− mice express lysozyme P.

Peritoneal exudate neutrophils were from (A) lys M^−/−mice and (B) F2 wild-type mice. Alveolar macrophages were from (C) lys M^−/− mice and (D) F2 wild-type mice. Cells were stained with antilysozyme antibody and counterstained with hematoxylin. Reactive cells stained red. Note that lysozyme is present in alveolar macrophages but absent in neutrophils of lys M^−/−mice. (E) Concentration of lysozyme in lung lavage (> 95% macrophages; pg/cell; left panel) and peritoneal exudate lavage (> 85% neutrophils; pg/cell; right panel). Error bars indicate SEM; asterisk, significant difference (P = .006) in lysozyme concentration. (F) Western blot analysis with antilysozyme antibody indicates that 1.4 × 10⁵ alveolar macrophages (left panel) or 100 μL BAL cell-free supernatant (right panel) from wild-type mice (“C”) contain only lysozyme M, while 1.4  × 10⁵ alveolar macrophages or 100 μL BAL cell-free supernatant from lys M^−/− mice contain only lysozyme P. M and P represent recombinant lysozyme M and P standards (Stds, 200 ng).