[Relative functional changes in neutrophils in early period of acute lung injury in rabbit]

To explore the relationship of interleukin-8 (IL-8), adherence function of neutrophil (PMN) and acute lung injury (ALI).

Eighteen male New Zealand rabbits were divided into two groups randomly: the control group (n=8) and the ALI group (n=10). The model of ALI was replicated by using intravenous lipopolysaccharide (LPS) in the rabbits of group ALI. Blood pressure, heart rate, blood gas analysis, hemogram, CD11b expression intensity on the surface of PMN, concentration of serum IL-8 and malondialdehyde (MDA) were measured at each time point. Specimens for pathology were obtained at the end of experiment.

In group ALI, blood pressure, heart rate and pH declined obviously. PMN count was lowered obviously at 3 hours and increased at 6 hours to some extent. CD11b expression intensity on the surface of PMN, the concentration of serum IL-8 and MDA were increased progressively (all P<0.05). The main changes in the microscopic examination were inflammatory granulocyte infiltration, disseminated thickening of alveolar septa and focal hemorrhages. There were significant correlations between CD11b and IL-8 (r2=0.813, Y=26.729X), and between CD11b and the grades of pathological changes at 6 hours after intravenous LPS (r2=0.771, Y=0.011 02X+5.292).

LPS could induce the release of large amount of IL-8, and it activates the expression of CD11b on the surface of PMN, which shows high degree of correlation with IL-8 and the degree of pathological changes in the lung. Therefore, both of them could serve as sensitive indexes for the diagnosis of ALI.