Differential requirement for protein synthesis in cytolysis mediated by class I and class II MHC-restricted cytotoxic T cells.

Antigen-specific cytolysis by major histocompatibility complex (MHC) class II-restricted cloned T-cell lines was found to be dependent on protein synthesis. Cytolysis by both polyclonal short-term and long-term class I-restricted cytotoxic T lymphocytes (CTL) was almost completely insensitive to inhibitors of protein synthesis. Kinetic studies with class II-restricted CTL indicated that approximately 2-3 hr after initiation of activation, resistance to inhibitors of protein synthesis was acquired. This strongly suggests that either a cytotoxic effector molecule or an intermediary important in the delivery of such a molecule is synthesized rapidly after activation in class II-restricted CTL, whilst class I-restricted CTL have no such requirement.