Neutralizing IL-10 leads to enhanced T cell responses in LCMVClone13-infected mice at day 8 post-infection. a) Splenocytes from mice infected with LCMVARM (left column), LCMVClone13 (middle column), or LCMVClone13 and given anti-IL-10 antibodies (right column), were stimulated with LCMV class I peptides, GP33-41 or NP396-404, class II peptides, GP61-80 and NP309-324 and control ovalbumin (OVA) peptides and IFNγ production was measured by intra cellular cytokine staining. Numbers below representative plots indicate the frequency CD69+ IFNγ+ T cells. The cells gated (CD4 or CD8) are indicated in parentheses. Plots are representative of 5 mice in each group. b) The total number LCMV-specific IFN-γ+ splenic CD8 and CD4 T cells from the mice infected with LCMVClone13, or LCMVClone13 treated with anti IL-10 are shown in open and hatched bars, respectively. Data from acutely-infected LCMVARM mice are shown in the filled bars for comparison. The LCMV peptides used for stimulation and the cell gating strategy are indicated below the graph. These data are representative from two independent experiments; the average of 5 mice per group is graphed. c) Anti-IL-10 treated, LCMVClone13-infected mice exhibit potent CTL responses. Splenocytes from uninfected or mice were infected with LCMVARM, LCMVClone13, LCMVClone13 plus anti-IL-10 were tested for CTL activity against target cells pulsed with LCMV NP396-404, GP33-41, or control OVA peptides (not shown), 8 days p.i. using a standard 51Cr release assay . d) LCMVClone13-infected mice receiving anti-IL-10 mAbs have lower viremia. Day 8 p.i. sera from LCMVClone13 infected mice with (filled circles) or without (open circles) anti-IL-10 treatment were tested for infectious virus by plaque assay ). e) Anti-IL-10 treatment did not lead to enhanced humoral responses at day 8 post-infection. Sera were collected from mice infected with LCMVClone13 with and without anti-IL-10 treatment at 8 days post-infection and LCMV-specific antibodies were assessed by ELISA. There was no statistical difference (p = 0.2) in the serum anti-LCMV antibody levels between these two groups.