Primary T-cells

[jplin at husc3.harvard.edu]

     I have a simple question regarding propagation of primary
T-cells in culture.  If one uses PHA, OKT3 or the like and IL-2 
containing medium, how long can the cells be maintained in culture?
How often do they need to be stimulated?  What concentration
(range?) of IL-2 is usually used?
     Sorry...  I guess that's more than one question.
     Thanks in advance for your help!

Jeff