Partially platelet-depleted mice fail to control an acute LCMV Armstrong infection and have exhausted LCMV-specific CD8⁺ T-cell responses. Mice were treated with PBS or 40 μg of anti-GPIIb antibody 12 hours before and, 2 and 4 days after LCMV Armstrong infection. (A) Viral titers found in serum, liver, and kidneys. Serum and organs of infected mice were recovered 8 days after infection. (B) Cytokine production by splenic virus–specific CD8⁺ T cells. IFNγ and TNFα production by splenocytes 8 days after infection after in vitro stimulation with the indicated peptides (cells gated on CD8⁺ events, numbers indicate percentage of cells in each region). (C) Total numbers of LCMV-specific CD8⁺ T cells in the spleen. Day 8 after infection tetramer positive populations (as indicated in the graphs) expressed as percentage of CD8+ cells (top panel) and as total cells per spleen (bottom panel). (A-C): Open bars, PBS-treated controls; black bars, anti-GPIIb–treated mice. Error bars represent SEM (*P < .05). One representative experiment of at least 2 is shown, with 5 animals per group per experiment.