Effects of a human plasma fraction on the release of chemotactic factors and anaphylatoxin from complement

A fraction prepared from normal human plasma inhibits the release of chemotactic factors and anaphylatoxin when complement is activated by the alternate but not by the classical pathway. The fraction gave no interference with the actions of the released substances on either leucocytes or guinea-pig isolated ileum. The possible relation of this effect to the mechanism of the anti-inflammatory actions of the plasma fraction is discussed.