An alternate complement pathway: C-3 cleaving activity, not due to C4,2a, on endotoxic lipopolysaccharide after treatment with guinea pig serum; relation to properdin.
The reaction between endotoxic lipopolysaccharide (LPS) and the guinea pig complement system was shown to proceed by way of an intermediate complex, LPS-X, which contains at least six guinea pig serum proteins. LPS-X, like [unk] (sheep erythrocytes carrying antibody molecules and [unk] complexes), destroys the C3 molecule by cleavage. On incubation at 37 degrees C, LPS-X loses its capacity to destroy C3 at about the same rate as the decay of [unk], so that it has been assumed that LPS-X carries [unk] sites that are responsible for the destruction of C3. We have now shown that monospecific rabbit antiguinea pig C2, which effectively inhibits C3 cleavage by [unk], does not interfere with the destruction of C3 by LPS-X. Furthermore, not more than a trace of C2a(d) is released from LPS-X on incubation at 37 degrees C. These results indicate that LPS-X does not carry a significant quantity of [unk] and, hence, that its capacity to destroy C3 is due to another factor which is presumably a component of the properdin system.
D000818:Animals; D002021:Buffers; D003165:Complement System Proteins; D004731:Endotoxins; D006168:Guinea Pigs; D006461:Hemolysis; D007106:Immune Sera / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000302:isolation & purification; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification; D011414:Properdin; D014678:Veillonella / Q000032:analysis
D002021:Buffers; D004731:Endotoxins; D007106:Immune Sera; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; D011414:Properdin; D003165:Complement System Proteins