Fig. 6

Immune effects of antimicrobial materials. a Nanomaterials with selective toxicity toward microorganisms can exert different effects on immune responses. They can recruit macrophages, neutrophils, dendritic cells, and natural killer cells, induce innate immune cell differentiation, promote the release of inflammatory cytokines, as well as kill pathogens. b Direct binding of Gram-positive or Gram-negative endotoxins (LPS or LP) by antimicrobial peptides blocks the binding of endotoxins to immune cell receptors like TLR4 or CD14. This results in the prevention of the over-activation of immune cells and the down-regulation of inflammatory responses and sepsis. c Bacteria or fungal antigens exposed on nanomaterials can be recognized by adaptive immune cells to activate Th, cytotoxic T cell as well as B cell adaptive immune responses, promoting bacterial clearance via opsonization mediated by complement and/or antibodies produced by B cells or direct killing of infected cells by cytotoxic T lymphocytes (CTLs). IL interleukin, TNF-α tumor necrosis factor-α, IFN-γ interferon-gamma, LPS lipopolysaccharide, LP lipoprotein, TLR4 Toll-like receptor 4, Th T helper