SIGLEC5 (sialic acid binding Ig like lectin 5) is involved in immunosppressiveness by interacting in a hemophilic manner. It interacts with acute phase protein a1-acid glycoprotein, group B streptococcal cell-wall-anchored β protein and the sialylated lipopolysaccharide of Neisseria meningitides. This protein recruits the phosphatases SHP-1 and SHP-2 to its intracellular ITIMs (immunoreceptor tyrosine-based inhibitory motif), which prevents the activation of kinase-dependent activation cascades. Unmasking of this protein is essential for the proinflammatory effect of S. pneumoniae desialylation of the leukocyte cell surface. Interaction of Group B Streptococcus (GBS) β protein with SIGLEC5 results in suppression of human leukocytes phagocytosis function, oxidative burst, and extracellular trap production. This leads to increased bacterial survival.
