Fig. 6

Intracytoplasmic cytokine-producing T cell frequency after stimulus with L. infantum SLA. Cytokine indexes were calculated as the ratio of cytokine⁺ cells observed in SLA-stimulated cultures divided by the control culture (SLA/CC ratio). Mice received saline (Saline: white rectangle), or were immunized with wild-type (WT Phage = light grey bars), B1 (B1 Phage = dark grey bars) or D11 phages (D11 Phage = black bars). Later, they were challenged with L. infantum promastigotes and, 60 days after infection, their splenocytes were collected and in vitro stimulated with L. infantum SLA (25 μg/ml). Results were reported as cytokine indexes (Stimulated culture/Control culture ratio) for IFN-γ, TNF-α, and IL-10 in a, b and c, respectively, for CD4⁺ T cells and in d, e and f, respectively, for CD8⁺ T cells, and were expressed as mean plus standard deviation of the groups. Letters above bars indicate a statistically significant difference in relation to the saline and WT phage groups, respectively (P < 0.05); asterisk indicates a statistically significant difference between CD8⁺ and CD4⁺ IFN-γ⁺ producing T cells (*P < 0.05); # indicates a statistically significant difference between CD4⁺ and CD8⁺ TNF-α⁺ producing T cells (^# P < 0.05)