TLR9 and infection: Enhanced pro-inflammatory cytokine production has been shown in response to TLR1/2, TLR4, TLR7/8 and TLR9 stimulation in PBMCs obtained from volunteers undergoing experimental malaria [58] or patients with natural infection [59], while others have suggested that malaria has a suppressive effect on TLR signalling, possibly through cross-tolerance following recognition of Plasmodium antigens by TLRs [60].