CD209 antigen-like protein B (SIGNR1) (SIGNR1)

CD209 antigen-like protein B, commonly known as SIGNR1, is a C-type lectin receptor primarily expressed on marginal zone macrophages in the spleen and specific dendritic cell subsets in mice (UniProt: Q8CJ91). It functions as a major pattern recognition receptor (PRR) that captures blood-borne pathogens, particularly encapsulated bacteria like Streptococcus pneumoniae, by recognizing capsular polysaccharides (PubMed: 12649300). SIGNR1 is also recognized for its role in the classical complement pathway, where it binds C1q to facilitate the deposition of C3 on pathogens (PubMed: 15153530). In the context of immunotherapy, SIGNR1 is a critical mediator of the anti-inflammatory effects of Intravenous Immunoglobulin (IVIG); it binds to sialylated Fc regions of IgG, triggering the release of IL-10 and subsequent suppression of autoantibody-mediated inflammation (PubMed: 16601191). While SIGNR1 is specific to rodents, its human functional homolog is often considered to be DC-SIGN (CD209), making it a vital target for studying glycan-based immune modulation and vaccine delivery strategies (PubMed: 12502732). Therapeutic targeting of this receptor aims to either enhance pathogen clearance or exploit its tolerogenic signaling to treat autoimmune disorders.

Other names

CD209bSpecific ICAM-3-grabbing non-integrin-related protein 1OtB7SIGN-related 1

Binding to sialylated Fc fragments of IgG to induce IL-10-mediated anti-inflammatory responses; recognition and capture of capsular polysaccharides for pathogen clearance and complement deposition.