Sequential release of TNFα and phospholipase A₂ in a rat model of LPS-induced pleurisy

Abstract

The levels of extracellular phospholipase A₂ (sPLA₂) and TNFα, and cell accumulation were measured in the pleural washings obtained at different times following the induction of Escherichia coli lipopolysaccharide (LPS, 100 μg/cavity) pleurisy in rats. TNFα peaked at 2 hours (3036 ± 160.3 units/ml) and decreased thereafter. Conversely, levels of sPLA₂ peaked at 48 hours (1.97 ± 0.64 ng/ml) and were increased further (14.02 ± 4.16 ng/ml) by pretreatment with anti-TNFα antibody. Cell accumulation was not affected by antibody pretreatment. These data indicate that the sPLA₂ enzyme is involved in LPS-induced pleurisy. The enzyme seems not to be stimulated by TNFα which may be involved in the downregulation of sPLA₂ in this model of inflammation.