In addition, while there was no significant difference in serum IFN-γ levels among the groups (Figure 6C), recipients of CD4+CD25+ T cells had significantly higher levels of proinflammatory cytokines (including TNF, IL-6 and MCP-1) than those that received CD4+CD25− or PBS on day 13 post-infection (Figure 6D–F). Here, CD4 is linked to infection.