Upon initial thawing, recombinant rat GM-CSF (Cat. No. 555111) should be aliquoted into polypropylene microtubes and frozen at -80°C for future use.Alternatively, the product can be diluted in sterile neutral buffer containing not less than 0.5 - 10 mg/mL carrier protein, such as human or bovine albumin, aliquoted and stored at -80°C.For in vitro biological assay use, carrier-protein concentrations of 0.5 - 1 mg/mL are recommended.For use as an ELISA standard, carrier-protein concentrations of 5 - 10 mg/mL are recommended.Failure to add carrier protein or store at indicated temperatures may result in a loss of activity.Carrier proteins should be pre-screened for possible effects in each investigator"s experimental system.Carrier proteins may have an undesired influence on experimental results due to toxicity, high endotoxin levels or possible blocking activity.

ELISA Standard:Recombinant rat GM-CSF (Cat. No. 555111) can be useful as a quantitative standard for measuring rat GM-CSF protein levels using sandwich ELISA.

Bioassay:Investigators are advised that the Bioassay application is not routinely tested for this material and are highly encouraged to both titrate this material and include appropriate controls in relevant experiments. Anactivity range of 0.1 - 1.0 x 10^9 units/mg, encompassing an

ED50= 10 - 100 pg/mL, has previously been reported using MC/9 as indicator cells in a proliferation assay, with a unit defined as the amount of material needed to stimulate a half-maximal response at cytokine saturation.