Examining a CTL-line (B6.1) with specific cytolytic activity, we have confirmed the ability of CTL-lines to produce poly C9-like, tubular complexes of two sizes (
polyperforin 1 and 2). Isolated cytoplasmic granules from this cell line can induce
hemolysis and contain the lysosomal marker
arylsulfatase. Electron microscopial studies show that granules contain precursor molecules which are assembled into
polyperforin upon addition of Ca2+.
Antibodies raised against granules predominantly react with a 27-kd
protein. We compared the B6.1 cell with a hybrid,
PC60, derived from a cross between B6.1 and a non-cytolytic rat-
thymoma. This hybrid line exhibits inducible CTL-activity. In
PC60 with induced cytolytic activity, polyperforins 1 and 2, cytolytic granules and granule-associated
proteins are detected. Non-cytolytic
PC60 cells lack cytolytic granules and
polyperforin 1, but contain
polyperforin 2. These results suggest that cytolytic granules appear in parallel with the expression of cytotoxicity during T-lymphocyte differentiation.