胶原凝集素（Collectin，简称胶凝素），是一种可溶性的模式识别受体，属于含有C-型凝集素的胶原蛋白。

目前已经有八种胶原凝集素被辨识出来，这包括甘露聚糖结合凝集素（Mannan-binding lectin，MBL）、表面活性蛋白A（Surfactant protein A，SP-A）、表面活性蛋白D（Surfactant protein D，SP-D）、肝胶原凝集素1（Collectin liver 1，CL-L1）、胎盘胶原凝集素1（collectin placenta 1，CL-P1）、共凝集素（Conglutinin，或译胶固素、团集素、高粘合素）、43千道尔顿胶原凝集素（collectin of 43 kDa，CL-43）与46千道尔顿胶原凝集素（collectin of 46 kDa，CL-46）。

Collectins (collagen-containing C-type lectins) are a part of the innate immune system. They form a family of collagenous Ca-dependent defense lectins, which are found in animals. Collectins are soluble pattern recognition receptors (PRRs). Their function is to bind to oligosaccharide structure or lipids which are on the surface of microorganisms. Like other PRRs they bind pathogen-associated molecular patterns (PAMPs) and also danger-associated molecular patterns (DAMPs) of oligosaccharide origin. Binding of collectins to microorganisms may trigger elimination of microorganisms by aggregation, complement activation, opsonization, activation of phagocytosis or inhibition of microbial growth. Other functions of collectins are modulation of inflammatory, allergic responses, adaptive immune system and clearance of apoptotic cells.