The enhancement of the haemolytic activity of the first component of complement by trasylol.

Trasylol, a basic polypeptide extracted from bovine lung considerably enhances the complement activity of whole serum. The complement component influenced by Trasylol is C1, either in its activated form (C1) or in its precursor form (C1). An effect on the binding of C1 to the immunoglobulin molecule has been excluded and on becoming part of a cellular intermediate C1 has been shown to be insensitive to Trasylol. It seems that Trasylol modulates C1 in such a way as to render it more efficient haemolytically. An attempt has been made to explain these results by consideration of the relationship existing between complement and other biological systems, such as the fibrinolytic and kallikrein-kinin systems.