Arrest of the cell cycle reduces susceptibility of target cells to perforin-mediated lysis

✍ Scribed by Marisela De Leon; Kimberly M. Jackson; Jay R. Cavanaugh; David Mbangkollo; C. Reynold Verret

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 146 KB
• Volume: 69
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(19980615)69:4<425::aid-jcb4>3.0.co;2-p

✦ Synopsis

Cytotoxic T lymphocytes secrete a pore-forming cytolysin, perforin, that damages membranes of target cells. They also ligate Fas receptors on target cells and provoke apoptotic death. A20 (B lymphoma) and P815 (mastocytoma) cell lines were examined for their susceptibility to perforin-mediated lysis and to Fas-induced apoptosis after blockade of the cell cycle at the G 1 /S interface. Cells were arrested at the G 1 /S interface by inhibition of DNA synthesis with thymidine or aphidicolin. Subsequently, the treated cells were incubated either with CTL cytotoxic granules or the Fas-specific monoclonal antibody Jo-2. We show that arrest of the cell cycle at the G 1 /S interface markedly reduced the susceptibility of target cells to perforin-mediated lysis. In contrast, growth arrest with thymidine or aphidicolin increased susceptibility of A20 and P815 cells to Fas-mediated apoptosis. Susceptibility to lysis by intact CTLs was not affected significantly by blockade of target cells with aphidicolin or thymidine. When cells surviving exposure to perforin-containing granules were isolated on Ficoll density gradients and cell-cycle profiles were examined by flow cytometry, the ratio of G 1 to G 2 cells increased among the survivors exposed to granules in contrast to controls incubated with buffer alone. The data suggest that cells in G 1 phase of the cell cycle are less susceptible to the perforin pathway than cells in G 2 and S phases but are more susceptible to the Fas pathway.