PMC

The interplay of sialylated bacterial pathogens with Siglecs expressed on neutrophils and macrophages. (A) Group B Streptococcus (GBS) and P. aeruginosa utilize surface sialic acids to engage the inhibitory Siglec-9, blunting neutrophil activation and bactericidal activity. GBS β-protein triggers inhibitory and activating signals on individuals expressing Siglec-5 and Siglec-14, respectively. (B) Sialoadhesin on macrophages recognizes multiple sialylated pathogens to promote phagocytosis and killing, inflammatory cytokine secretion and enhanced antibody responses. However, HIV uses sialoadhesin-mediated sialic acid recognition to facilitate its trans-infection. Like neutrophils, GBS β-protein triggers inhibitory and activating signals on individuals expressing Siglec-5 and -14, respectively.