Anti-inflammatory and irritant effects of a fraction from normal human plasma.

1 By the use of carrageenan-induced rat paw oedema assay the anti-inflammatory activity of a fraction isolated from normal human plasma has been measured after its intravenous, intraperitoneal and oral administration. Its effects in the dextran-induced rat paw oedema and the systemic dextran anaphylactoid reaction in the rat were also studied.2 The fraction showed marked anti-inflammatory activity in the carrageenan test after intravenous administration and a smaller but still significant activity when given intraperitoneally, but was inactive orally after the administration of a larger dose. It was active in the dextran-induced paw oedema test but not against the anaphylactoid reaction.3 A comparison between its anti-inflammatory and irritant properties revealed no correlation when each parameter was determined in relation to dose. The fraction did not affect the blood pressure of the anaesthetized rat.4 These findings are discussed in relation to the existence of a natural anti-inflammatory substance or substances in human plasma.