Adult Rabbit Complement, Adsorbed

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.

Use the adsorbed complement for HLA-DR tissue typing and lymphocytotoxicity crossmatch on human cells: it is adsorbed with human buffy coat and red blood cells of mixed blood types, which removes the rabbit's natural antibodies to human cells and keeps background lysis low. The unadsorbed complement suits HLA-ABC typing and general complement-dependent cytotoxicity work where that background is not limiting.

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.

Endogenous complement activity can cause intrinsic, non-specific bacterial killing. We recommend preventing this by heat-inactivating all OPA/OPKA antisera at 56°C for 30 minutes, and always running controls of complement, HL60 cells and bacteria without antiserum to assess non-specific killing. If you are still seeing higher than expected non-specific killing, try the following:
• Run the assay with a new aliquot of bacteria, in case the original was compromised in a way that made it easier to kill.
• Use a different bacterial strain to see if you can replicate the finding.
• Test a new HL60 cell preparation, preferably at a higher or lower passage number.

Yes, you can request products that originate from a single lot or from several different lots. We are usually able to accommodate these requests but availability may vary due to maximum lot volumes for certain products. We try to maintain a minimum inventory of ten 5+ liter baby rabbit complement (BRC) lots at all times so that customers have options to select from. We recommend that you contact us directly with your request on our contact page or by emailing biosales@pel-freez.com.