CTL of pearl mice are impaired in degranulation and cytotoxicity. CTL from C57BL/6, pearl, ashen, and PKO mice were analyzed 8 days after infection with 200 pfu of LCMV-WE. Degranulation of LCMV-specific CTL was analyzed after in vitro restimulation with the gp33 peptide. (A) Representative fluorescence-activated cell-sorting plots gated on CD3⁺CD8⁺ lymphocytes are shown. Numbers indicate the percentage of CD107a⁺ cells among gp33-specific IFN-γ⁺ CTL. (B) Frequencies of CD107a⁺ cells of IFN-γ⁺CD8⁺ T cells were analyzed. Pooled data from 3 independent experiments are shown. ***P < .001 (C) Wild-type mice were infected with 10⁴ pfu LCMV. Then, 10 hours later they were adoptively transfused with 2 × 10⁶ isolated day 8 splenic CTL of either wild-type or pearl mice and after additional 18-hour splenic virus titers were analyzed. Pooled data from 2 independent experiments with 3-4 mice per group are shown. The dashed line indicates the detection limit. Nil indicates without transfer. (D) Ex vivo cytotoxicity was tested in a 5-hour ⁵¹chromiumrelease assay on either LCMV-infected MC57 target cells (left) or gp33 peptide-loaded EL-4 target cells (right). Results from 1 of 2 independent experiments with 3 mice per group are shown.