Death of KC targets in vivo is slow and not readily amenable to direct intravital imaging.28, 29 We have previously used prolonged time-lapse imaging of primary target and effector cells in vitro to show that the mechanism of killing was associated with T-cell kinematics.28 We utilized this method to determine the role of IFNγ in CTL cytotoxicity to keratinocytes. The gene discussed is IFNG; the disease is keratoconus.