Chitinase-3-like Protein 1 (CHI3L1)

Cartilage glycoprotein-39 is one of the major secreted proteins of ex vivo cultured human articular chondrocytes, synovial cells, and macrophages and also expressed by mature neutrophils (from myelocyte-metamyelocyte stage). High levels of YKL-40 are found in synovial fluid from patients with active rheumatoid arthritis (RA) and in the hippocampus of schizophrenic patients. YKL-40 belongs to the 18-glycosyl hydrolase (mammalian chitinase) family, and is one of the putative autoantigens in rheumatoid arthritis (RA). High levels of YKL-40 are found in synovial fluid from patients with active RA. The name 'YKL' stands for its N-terminal tripeptide sequence, and unlike the other member YKL39 which is unglycosylated, YKL40 is glycosylated.