Collectin

Collectins are a family of soluble pattern recognition receptors (PRRs) that serve as a primary line of defense in the innate immune system (PMID: 10837054). Structurally, they are characterized by a collagen-like region and a C-type carbohydrate recognition domain (CRD) that allows them to bind to specific sugar patterns on the surfaces of bacteria, viruses, and fungi (UniProt: P11226). Major human collectins include Mannan-binding lectin (MBL), which circulates in the blood, and Surfactant proteins A and D (SP-A and SP-D), which are primarily found in the lungs (PMID: 11739550). Upon binding to pathogens, collectins facilitate opsonization, enhance phagocytosis by immune cells, and can activate the lectin pathway of the complement system (PMID: 15128857). They also play a vital role in maintaining homeostasis by clearing apoptotic cells and modulating inflammatory signaling (PMID: 21169542). Therapeutic applications include replacement therapies for MBL deficiency and the use of recombinant surfactant-based collectins to treat neonatal respiratory distress syndrome and other pulmonary conditions (ClinicalTrials.gov: NCT04659122).

Other names

Collagen-containing C-type lectinGroup III C-type lectinSoluble pattern recognition receptorMannan-binding lectinSurfactant protein ASurfactant protein DCollectin-10Collectin-11Collectin-12

Collectins act by binding to carbohydrate patterns on pathogens via their C-type lectin domains, which triggers the lectin pathway of complement activation and enhances phagocytosis through opsonization (PMID: 15128857). They also modulate the inflammatory response by interacting with cell surface receptors like calreticulin/CD91 to facilitate the clearance of apoptotic debris (PMID: 21169542).