Human cathepsin S ELISA kit is used for quantitative detection of human Cathepsin S in cell culture supernates, serum and plasma (heparin, EDTA).

Cathepsin S, also known as CTSS, is a protein that in humans is encoded by the CTSS gene. A member of the peptidase C1 family, CTSS gene is a lysosomal cysteine proteinase that may participate in the degradation of antigenic proteins to peptides for presentation on MHC class II molecules.

By fluorescence in situ hybridisation (FISH), this gene is mapped to 1q21.3. The encoded protein can function as an elastase over a broad pH range in alveolar macrophages. The bond-specificity of this proteinase is in part similar to the specificities of cathepsin L and cathepsin N.