Resistance of normal, unstimulated, CD8+ T cells to lysis by cytotoxic granules from cloned T cell lines

Abstract
Previous work has shown that both long-term cloned cytotoxic T lymphocyte (CTL) lines and primary CD8+ CTL are resistant to lysis by the toxic granules purified from long-term cloned CTL cell lines. We show here that normal, unstimulated CD8+ spleen and thymus cells are also relatively resistant to lysis by these granules. Using flow cytometric analysis we demonstrate that CD8+ T cells in normal spleen and thymus cell populations are enriched by subjecting the total cell population to lysis by cytolytic granules. Similar enrichment was not seen when the total cell populations were subjected to lysis by melittin, an unrelated, cytolytic, pore-forming polypeptide.