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

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 ofEscherichia colilipopolysaccharide (LPS, 100 μg/cavity) pleurisy in rats. TNFα peaked at 2 hours (3036 ± 160.3 units/ml) and decreased thereafter. Conversely, levels of sPLA2peaked 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 sPLA2enzyme is involved in LPS-induced pleurisy. The enzyme seems not to be stimulated by TNFα which may be involved in the downreg…