Recombinant interleukin-1 triggers the increase of circulating fibronectin level in rats

Interleukin-1 (IL-1) is one of the mediators responsible for the acute phase protein response during inflammation. We evaluated the effect of recombinant IL-1 alpha given intra-abdominally on rat circulating fibronectin (Fn) levels. Circulating Fn level, sampled between 3 h and 7 days after injection, was maximum at 24-48 h in Wistar rats treated with IL-1 at doses of 10 U and 100 U/100 g body weight (BW), respectively. Circulating Fn level in rats injected with 100 U/100 g BW IL-1 was higher than that of rats given 10 U/100 g BW IL-1. Circulating Fn level peaked at 24 h, whereas albumin levels decreased by 10% at this time. When frozen tissue sections of rat liver were examined using anti-Fn antibodies, the immuno stainings were denser in IL-1-treated animals than in controls. These findings suggest that IL-1 triggers plasma Fn production by the liver.