convert IL-2 unit to mass - (Oct/06/2011 )

Hi I have a bottle of IL-2 cytokine from R&D system (402-ML) and it is 20ug. I need to calculate how much I need to get 100 U/mL. On R&D website, it says the ED50 is 0.5ng/mL and the its 2.5X10^5 U/ug. Can someone help me please!

20 ug of powder
250,000 U/ug
5,000,000 U/bottle

Reconstitue vial with 1 ml of water yields: 20 ug/ml or 5,000,000 U/ml

make a 1:500 dilution yields 10,000 u/ml; then 1:100 yields 100 U/ml

If the protein is expensive and can be frozen save your dilutions in microfuge vials at -80C; use multiple vials to avoid freezing and thawing your stock material.