Processing of perforin to the mature form is impaired in patient CTLs. Western blots of CD8⁺ CTL lysates from control (lanes 1,3) and patient (lanes 2,4), showing immature, intermediate, and mature forms of perforin in control CTLs, and only the immature and intermediate forms in patient 6¹² . Longer (top) and shorter (bottom) exposures of lysates from NK cells from control (lanes 5-6) or patient 6 (lanes 7-8) were incubated in the presence (lanes 5,7) or absence (lanes 6,8) of Endo H and probed with 2d4-antiperforin. All samples were run on 7.5% acrylamide gels under nonreducing conditions.