reprokine’s cytokine products are generaly prepared from sterile filtered buffers in a pH range of 5.0-7.0. In certain cases we may add sugar additives as stablizers, however no protein stabilizers (such as BSA,HSA) are used in the formulations.
Cytokines are known to be sensitive and do not like to be alone in the tube in a liquid state for prolonged periods.
Properly lyophilized products exhibit better lifespan and stability, and may be stored without detectable loss of activity for years.
Endotoxin is a bacterial LPS found on gram-positive bacteria and a known pro-inflammatory protein, an endotoxin contamination will trigger cells to secret different cytokines.
At reprokine we understand the importance of recieving your cytokines endotoxin free (below 1EU/ug).
For optimal extraction of cytokine from vial we recommend the following:
1.Dispense recommended volume into the vial, most of the lyophilized pellet should lie at vial bottom.
2.To maximize product collection from vial surface, vortex first and then spin down to recollect the dispensed volume.
After reconstituting your cytokines, we recommend short-term storage at 4C. For longer term storage, the protein solution should first be aliquoted (to avoid more than one freeze/thaw cycle) and stored frozen at -20C. Please keep in mind that every freeze/thaw cycle may cause some denaturation of the protein.
A cytokine activity is measured by its ability to function within a cellular environment. The function of a cytokine varies between cytokines and the effects measured can be proliferation,chemotaxis,viral resistance, secretion of cytokines…etc.
The parameter to describe cytokine activity is the ED50 (half maximum Effective Dosage), a measure of the required concentration needed to achieve 50% maximal response.
1 Unit of activity is defined as the ED50 value.
While this is a wholly relative way to quantify activity, dependent on how each activity assay was performed, the WHO does provide standardization to cytokine activity via reference materials with established assays and units of activity IU(international units).
Most probably not, it is very common that no pellet is visible when vial contents are a few micrograms. The remaining pellet is always the residue of buffer constituents and additives. When none are used then it is likely that the pellet will be hardly visible.
With a few exceptions, most human cytokines are active on mouse cells. Many mouse cytokines are active on human cells, but may show lower specific activity than the corresponding human cytokine.