unprimed ly-1+2+ cells gave rise to ctl in the absence of the other subsets , while unprimed ly-1+2- and ly-1-2+ cells required the help of ly-1+2+ cells ( or soluble factors ) during priming to become non-lytic ctl precursors by day 5 , and cytolytic cells after restimulation .
C1536403
cytolytic
C0007634
cells