The C3 component is central in both complement activation pathways, with different specific proteolytic systems cleaving it to form C3 convertase. Cleavage of C3 releases C3a and the C3b fragment which is part of the alternative C3 convertase. C3 levels can be low because of decreased synthesis or due to consumption. High C3 levels are seen in highly acute or chronic inflammation, hepatic cholestasis and during the third trimester of pregnancy. C3c has a mol wt of approx 137kDa. The common form present in plasma and used in diagnostics assays is the C3c form offered here. Scipac’s C3c product contains the intact Beta chain and the Alpha chain without the C3dg, C3a and C3f peptides. P150-0 should be suitable for raising polyclonal antibodies to C3.