Sample storage for ELISA (cell culture supernatant) - (Apr/22/2013 )

Hello everybody.
I have a question regarding ELISA.
my sample is cell culture supernatant. usually, for long storage, at what degree I should store my sample?
Is that Ok if I store at -70C? instead of -20C?

-70 should be fine.

tHANK YOU VERY MUCH