SP-40,40 is an inhibitor of C5b-6-initiated haemolysis
- 1 November 1989
- journal article
- research article
- Published by Oxford University Press (OUP) in International Immunology
- Vol. 1 (5) , 551-554
- https://doi.org/10.1093/intimm/1.5.551
Abstract
This study examines the function of SP-40,40, a newly identified component of the SC5b-9 complement complex, In the regulation of the terminal complement pathway. Purified SP-40,40 was shown to inhibit, in a dose-dependent manner, C5b-6-initiated haemolysls. Apparently additive inhibition was also demonstrated in conjunction with complement S-protein, although SP-40,40 appears to be the more potent inhibitor on an equimolar basis. The data suggest that SP-40,40, like S-protein, probably combines with the nascent C5b7 complex, forming a cytolytically inactive SC5b7-SP-40,40 complex. Preparations of S-protein, purified by an established technique, were shown to be contaminated with SP-40,40. Preparations of affinitypurified SP-40,40 were also shown to contain S-protein, suggesting that these proteins may be partially complexed in plasma.Keywords
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