Human Complement Kit, Pooled, IgG/IgM/IgA Depleted

Multiple freeze-thaw cycles will result in reduced complement potency, so we offer a variety of pack sizes to satisfy applications ranging from small scale assay development experiments to large scale clinical studies. We recommend limiting the number of freeze-thaw cycles and sub-aliquot into single-use quantities whenever possible in order to extend the shelf life of all of our complement products.

The hemolytic titer measures how well complement lyses antibody-sensitized sheep red blood cells; CH50 is the dilution of serum that lyses 50% of the cells. It is the release test for every lot of our complement products, and our heat-inactivated human products are CH50 tested to confirm that complement activity is absent.

Work backwards from the readout. Complement regulators are host-specific, so the complement source is part of the assay method, not a preference.

• Antibody-depleted human complement for the hSBA (serogroup B meningococcus and gonococcus; correlate hSBA ≥ 1:4). Neisseria recruits human factor H, which rabbit and guinea pig factor H cannot replace, and the donor antibodies in native human serum would kill the target on their own.
• Baby rabbit complement for the rSBA (serogroups A, C, W and Y; correlate rSBA ≥ 1:8) and for pneumococcal OPA/MOPA, which was standardized on it.
• Adult rabbit complement for complement-dependent cytotoxicity and HLA crossmatching, the classical cell-lysis source.
• Guinea pig complement where potency per volume is the point: CH50 titration, complement fixation and the vibriocidal assay.

When the model animal's own cascade is the readout, use matched-species complement. Mouse, rat, pig, canine, cynomolgus, goat and hamster complement are available on request through our custom quote form.

For what the research literature actually uses, by pathogen and assay, see which complement source for which assay.

Each depleted serum has a single complement component (C1q, C1r, C1s, C2 through C9, or factor B, D, H, I or P) removed, so the affected pathway stalls until that component is added back. They are used to study the role of one component, as reagents in functional complement assays, and as controls in add-back experiments.

Pooled products combine material from multiple donors, which averages out donor-to-donor variation and gives large, uniform lots. Single-donor products come from one donor: their properties trace to that donor and can differ more between lots. Studies that need a single, well-characterized source, such as one complement lot carried through a clinical trial, use single-donor material.

Human complement is the required complement source for the hSBA, the serum bactericidal assay used to evaluate serogroup B meningococcal vaccines such as 4CMenB and MenB-fHbp and the pentavalent MenABCWY vaccines. Neisseria binds human factor H to evade human complement, an interaction rabbit complement does not reproduce. Publications citing our human complement also cover Neisseria gonorrhoeae bactericidal assays and vaccine candidates, native outer membrane vesicle vaccines, and factor H and NspA binding studies.