Anti-CHI3 antibodies are protein reagents that detect specific antigens. The CHI3 antigen is another term for the human protein chitinase 1, encoded by the CHIT1 gene. The protein is known to function in immune response pathways, among other biological roles. Canonically, it has an amino acid length of 466 residues and a mass of 51.7 kilodaltons. Its subcellular localization is in the lysosomes and is secreted. It is notably expressed in spleen. The CHI3 protein is a member of the Glycosyl hydrolase 18 protein family. Other alias names for CHI3 include CHIT and CHITD.