Figure 6. Virus-specific antibodies enhance priming and expansion of CD8⁺ T cells.

(A) Graph showing the total neutralizing antibodies in naïve serum (WT, naive), serum from memory C57BL/6 mice (WT, LCMV) on day 100 and from KL25 mice (KL25, LCMV) on day 10 after infection with 2 × 10⁶ PFU of LCMV-WE and determined by in vitro neutralization assay (n = 4–5). (B–E) Naïve C57BL/6 mice were injected with non-specific antibodies or LCMV-specific antibodies. Mice treated with non-specific antibodies were infected separately with 2 × 10², 1 × 10³, 5 × 10³, or 2 × 10⁴ PFU of LCMV-Docile. Mice treated with LCMV-specific antibodies were infected with 2 × 10⁴ PFU of LCMV-Docile. (B) Viral titers in various organs after 10 days of viral infection (n = 6). (C) FACS plots representing the frequency of LCMV-specific Tet-GP33⁺ CD8⁺ T cells in blood (upper plots) and spleen (middle plots) after 10 days of infection. Lower plots show the frequency of interferon (IFN)-γ⁺ CD8⁺ T cells in spleen after 10 days of viral infection and in vitro stimulation with LCMV GP33 peptide (n = 6–9). (D) Total number of LCMV-specific Tet-GP33⁺ CD8⁺ T cells in spleen after 10 days of viral infection (n = 6–9). (E) Total number of IFN-γ⁺ CD8⁺ T cells in spleen after in vitro stimulation with LCMV GP33 peptide on day 10 of infection (n = 6–9). Horizontal dotted lines designate the detection limit. Data are shown as mean ± SEM and are pooled from 2 or 3 independent experiments. *P < 0.05; **P < 0.01; ***P < 0.001 (Student’s t-test).