Biological Activity: The ID50 of TGF-b1 on TF-1 cells in the presence of 2ng/ml GM-CSF was determined as 5-10ng/ml.
Quality Control:
ATP-Endpoint Assay for Cell Number: TF-1 cells were starved for serum and GM-CSF by overnight incubation in RPMI, 2% FBS. Cells were then incubated in RPMI, 2% FBS, 2ng/ml GM-CSF minus or plus varying concentrations of TGFb1. At the end of three days, cell number was determined using the ATP endpoint assay, ViaLight(TM). The ID50 was determined as the TGFb1 concentration that gave the half maximal response obtained by cells grown in RPMI, 2% FBS, 2ng/ml GM-CSF alone. (ViaLight(TM) is a trademark of LumiTech, Ltd.).
Storage and Stability: Lyophilized powder may be stored at -20 degrees C. May be stored at 4 degrees C for short-term only. Reconstituted product is stable for 12 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.