The protective effect of CD40 ligand–CD40 signalling is limited during the early phase of Plasmodium infection

• Agonistic anti-CD40 mAb (1C10) can enhance dendritic cell activation.
• Anti-CD40 mAb (1C10) can substitute for γδ T cells during early Plasmodium infection.
• CD40L expression on γδ T cells is maintained during Plasmodium infection.

γδ T cells are essential for eliminating Plasmodium berghei XAT. Because administration of the agonistic anti-CD40 antibody can induce elimination of P. berghei XAT parasites in γδ T cell-deficient mice, we considered that γδ T cells might activate dendritic cells via CD40 signalling during infection. Here we report that administration of the anti-CD40 antibody to γδ T cell-deficient mice 3–10 days post-P. berghei XAT infection could eliminate the parasites. Our data suggest that dendritic cell activation via γδ T cells expressing CD40 ligand is critical during the early phase of infection.