Partial liquid ventilation does not affect BALF TNF-, MIP-2, CINC-1 concentrations, or CD11b cell surface expression, but does increase macrophage proportion among BALF cells in the acute phase of rat LPS-induced lung injury

To elucidate the mechanism of anti-inflammatory effect of partial liquid ventilation (PLV), cytokine concentration, surface CD11b, and macrophage expression were investigated in BALF. The 30-minutes group was treated with gas ventilation (GV) for 30 minutes after intratracheal LPS administration. The GV group was prepared in the same manner as the 30-minutes group, then the GV was continued for the following 2 hours. The PLV group was treated in the same manner as the 30-minutes group, and then received PLV with perflubron for the following 2 hours. Animals were euthanized to receive BAL. The PLV group showed a tendency to have a higher concentration than the GV group of TNF-alpha, MIP-2, and CINC-1 as measured by ELISA, although there were no significant differences. The ratio of expressions of CD11b and macrophages to total leukocytes were determined by flow-cytometry. There were no significant differences in the ratio of CD11b-positive expression to acquired cells (GV: 63.6 +/- 8.4%, PLV: 60.5+/-5.4%, P=0.73). However, the proportion of macrophages was significantly increased (GV: 5.6 +/-1.5, PLV: 14.0+/-1.3, P=0.006). These results suggest that the anti-inflammatory effect of PLV is not caused by the change in CD11b expression, and that PLV affects the proportion of macrophage among BALF cells.