A low molecular weight proinflammatory factor from rat spleen lymphocytes. Isolation and partial characterization.

A dialyzable low molecular weight proinflammatory factor (X (2)) from rat spleen lymphocytes was isolated through a combination of gel filtration and high voltage paper electrophoresis (HVE) and then partially characterized. It was able to potentiate the formation of carrageenin induced edema on the rat paw. Its amino acid analysis revealed Glu, Cys and Gly (1:1:1), but gammaGlu as N-terminal residue, initially suggesting oxidized glutathione (GSSG), since it showed exactly the same HV electrophoretic mobility as GSSG at pH 6.5. However, neither GSSG nor a synthetic homologue showed any proinflammatory activity. On basis of its infrared spectrum, HVE mobility and presence of a gamma-Glu-Cys-Gly (GSH) moiety, the hypothesis of identity of X (2) with leukotriene C(4) (LTC(4)) was raised. Once again it was not confirmed, since LTC(4) did not show any proinflammatory activity too, leading us to infer that, even excluding LTC(4), our data are consistent with a structure bearing a GSH moiety conjugated with a hydroxylated insaturated fatty acid chain which contributes a -COO(-) group, thus providing a final net charge of -2 at pH 6.5 and an Mr = 600-650.