C1s depleted serum (C1s-Dpl) is normal human serum depleted of C1s by immunoaffinity chromatography. The product is tested for the absence of C1s by functional assays for classical pathway activity and for C1s protein by double immunodiffusion. C1s-Dpl is certified to possess a functional alternative pathway for complement activation (Morgan, B.P. (2000); Dodds, A.W. and Sim, R.B. (1997)).
In serum C1s is present in its proenzyme form (Valet, G and Cooper N.R. (1974); Ziccardi, R.J. and Cooper N.R. (1976)). C1s enzyme is the activated form of C1s proenzyme. C1s is a subunit of the C1 complex which is the first component in the classical pathway of complement (See product description for C1 Cat# A098). C1s proenzyme is an inactive zymogen until C1 is activated. C1r is activated when C1 binds to and is activated by antibodies bound to antigens (immune complexes) yielding C1r enzyme, the first protease that initiates the cascade. C1r enzyme in the C1 complex activates C1s proenzyme generating C1s enzyme. A functional classical pathway can be reconstituted by addition of purified C1s proenzyme (31 µg/mL) to the C1s-Dpl indicating that all other complement components necessary for classical pathway activation are present and active.
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