Anti-NS antibodies are protein reagents that detect specific antigens. The NS antigen is another term for the human protein serine peptidase inhibitor Kazal type 5, encoded by the SPINK5 gene. The protein is known to function in cell differentiation and nervous system development, among other biological roles. Canonically, it has an amino acid length of 1064 residues and a mass of 120.7 kilodaltons. It is a secreted protein and it is reported to be highly expressed in the thymus and stratum corneum.