Figure 4.

Extracellular Ca²⁺ is required for perforin/granule exocytosis and FasL/Fas-mediated cytotoxicity. 14-7 (a, b, d) and 14-7FD (c) were pretreated for 40 min with nifedipine, EGTA, SK&F-96365, NDGA, or Ni²⁺ at various concentrations before the start of a ⁵¹Cr cytolysis assay (a–c) or before anti-CD3ε stimulation (d). 14-7 was incubated with HA529–537 peptide (0.01 μM)–pulsed L1210Fas target in a ⁵¹Cr–release assay (a), and supernatants from a were used to measure granzyme A activity in a granule exocytosis assay (b). 14-7FD was incubated with HA529–537 peptide (0.01 μM)–pulsed L1210Fas⁺ targets in a ⁵¹Cr–release assay (c). 14-7 was stimulated with plate-bound anti-CD3ε for 6 h before staining for FasL with the Fas.Fc fusion protein by flow cytometry (d). All figures are representative of at least three separate experiments.