This decision is based on what cells you need to lyse and from what species the cells are from. Typically any type of complement should lyse cells, however we have made different formulations to enhance performance and reduce non-specific toxicity in certain assays. Listed below (and in our catalogue) are some general guidelines:
- Standard Rabbit Complement is mainly used for HLA-ABC tissue typing or cytotoxicity assays using human T cells.
Low-Tox complement formulations are processed to reduce the toxicity of the complement. They are used for cells that may be sensitive to non-specific lysis.
- Low-Tox-H is mainly for HLA-DR tissue typing (human B cells).
- Low-Tox-M is for cytotoxicity assays using mouse lymphocytes.
- Low-Tox-R is for cytotoxicity assays using rat lymphocytes.
- Baby Rabbit Complement and Baby Rabbit Complement-Tissue Culture Grade are used for cytotoxicity assays which requires the C to have low toxicity while maintaining a relatively high activity (higher than the Low-Tox formats, but lower that the standard rabbit C). Furthermore, the Baby Rabbit Complement-Tissue Culture Grade can be used for assays requiring the C to be sterile, virus and mycoplasma-free, and low in endotoxin.
- Rabbit Complement MA is screened for use in cytotoxicity assays using monoclonal antibodies against human lymphocytes.
- Standard Guinea Pig Complementis mainly used for hemolytic plaque assays and complement fixation assays. The Hemo-Lo format is used for sheep RBC hemolytic assays, and the Low-Tox GPC is mainly for cytotoxicity and plaque assays.
This type of complement will have low background toxicity (i.e. few cells will be lysed non-specifically).
This varies in each assay, therefore we recommend that you titrate to find your optimal dilution. Generally, a 1:8-1:16 dilution should be suitable (1:2-1:4 should be used for microlymphocytoxicity/tissue typing assays). Additional information may be found on the product data sheet.
Generally, the expiry is 2 years from date of manufacture for all of our complement formulations.
You may be able to use complement that has recently expired, however we cannot guarantee its performance. Should you decide to try it, we recommend using more (i.e. lower dilution) due to possible loss of activity.
Yes. If the complement is frozen to -70℃ (in single use aliquots) immediately after reconstitution it can be used, however only one freeze / thaw cycle is recommended.
The isotype of my primary antibody will not fix complement. Can I use a secondary antibody that fixes complement to deplete cells labeled with this primary antibody?
This has been tested in the past but with limited success. Therefore, we do not recommend it.
You can sterile filter your complement using a 0.22 µm filter; however you must dilute your complement first to your optimal dilution before filtering. Otherwise, you may lose complement activity because of the filtration process. You can also use the Baby Rabbit Complement-Tissue Culture Grade which is sterile.
There is no difference in quality. Lyophilized complement should be stored at 20℃, and frozen complement must be stored at 80℃. The lyophilized product will last longer, is more stable, and is easier to ship (dry ice is required to ship frozen complement).