Sialic acid-binding Ig-like lectin 1 (SIGLEC1)

Sialic acid-binding Ig-like lectin 1 (SIGLEC1), also known as CD169 or Sialoadhesin, is a large type I transmembrane receptor primarily expressed on myeloid cells, including specific macrophage subsets and interferon-induced monocytes [1, 3]. As a member of the Siglec family of I-type lectins, it mediates cell-cell adhesion and pathogen recognition by binding to alpha-2,3-linked sialic acids on the surface of glycoproteins and glycolipids [4, 12]. SIGLEC1 acts as an endocytic receptor that facilitates the capture and internalization of sialylated antigens for presentation to lymphocytes, thereby bridging innate and adaptive immunity [1, 16]. In viral diseases, it serves a dual role; while it acts as a sentinel to filter pathogens in the lymph nodes, it can be exploited by enveloped viruses such as HIV-1, Ebola, and SARS-CoV-2 to facilitate trans-infection of target cells [3, 4, 13]. Due to its sensitive upregulation by Type I interferons, SIGLEC1 is a robust biomarker for monitoring disease activity in autoimmune conditions like systemic lupus erythematosus and for the early diagnosis of acute viral infections [7, 11, 15]. Current therapeutic strategies focus on using monoclonal antibodies to block viral hijacking or leveraging its endocytic capacity for the targeted delivery of immunoconjugates [4, 16].

Other names

CD169SialoadhesinSNSiglec-1

Targeted delivery of therapeutic payloads via receptor-mediated endocytosis; blockade of viral attachment and trans-infection; pharmacological induction of cell-surface expression as a biomarker of immune activation [4, 5, 16].