An evolutionary perspective on C-type lectins in infection and immunity

Host-pathogen interactions have coevolved for many years. On the one hand, the human immune system consists of innate and adaptive immune cells that function to defeat pathogens, and on the other hand, pathogens have coevolved to use the system for their own propagation. C-type lectins are conserved receptors recognizing carbohydrate structures on viruses, bacteria, parasites, and fungi. C-type lectins such as DC-SIGN, langerin, and dectin-1 are expressed by dendritic cell subsets and macrophages. Pathogen recognition by C-type lectins triggers signaling pathways that lead to the expression of specific cytokines which subsequently instruct adaptive T helper immune responses. T helper cell differentiation is crucial for initiating proper adaptive immune responses; some pathogens, however, use pattern recognition receptors like C-type lectins to subvert immune responses for survival. This review provides an update on the role of C-type lectins in HIV-1, mycobacterial, and Candida infections, and the coevolution of hosts and pathogens.