Plg expression and Pla activity during a self-resolving model of inflammation. BALB/c mice were injected with LPS (250 ng per cavity, i.pl.) or PBS (i.pl.). Cells present in the pleural cavity were harvested at the indicated time points and processed for total cell counts in a Newbauer chamber and for differential leukocyte counts by light microscopy of cytospin preparations (A), western blot analysis for Plg (B), and measurement of Pla activity (C). The pleural cellularity was expressed as the number of leukocytes per cavity and is shown as the mean ± SEM of at least 4 mice in each group. *P < .05; ***P < .001 when compared with mice injected with PBS. ^#P < .05; ^##P < .01; ^###P < .001 when compared with mice injected with LPS for 8 hours. ^&&P < .01; ^&&&P < .01 when compared with mice challenged with LPS for 24 hours. Blots are representative of 3 independent experiments using pooled cells from at least 5 animals. For loading control, membranes were reprobed with anti–β-actin. For the Pla activity assay, results are expressed as plasmin activity unities mean ± SEM of at least 5 mice. ***P < .001 when compared with the untreated group.