Wittrup: Freezing Protocol
The following protocol gives instructions for freezing down aliquots of cultures for future use.
Lift and count cells using cold media.
Resuspend 3-5e6 cells in 0.5-1.0 ml cold freezing media, and transfer to a freezing vial.
Wrap the vial with parafilm.
Place in a freezing tray overnight.
The next day move the vials to liquid nitrogen storage (preferably in the vapor phase of the tank).
It is advisable to keep several vials of frozen cells on hand for any cell line in use.