Streptokinase does not activate the complement system

Streptokinase is an extensively used thrombolytic agent. However, different preparations cause severe hypotension during therapy, partially related to the complement cascade activation. In four ischaemic stroke patients treated with Streptase, an increased level of soluble terminal complement complex (SC5b-9) was measured. In the sera of normal subjects, the increase in SC5b-9 induced by Streptase, Kabikinase and Calbiochem streptokinases was highly significant (P < 0.005). Sigma streptokinase did not activate the complement system. Sigma streptokinase analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed a homogeneous band. The other three preparations were contaminated with albumin and other proteins. Based on our in vivo and in vitro data, we conclude that complement activation is related to contamination of different streptokinase products rather than the streptokinase itself.