Human
cathepsin W (
lymphopain) is a
cysteine protease that is restrictively expressed in cytotoxic cells, in particular NK cells. Several anti-
cathepsin W monoclonal antibodies were tested with respect to their capability to detect
cathepsin W by Western blot analysis and immunohistochemistry. Subsequently, the distribution of
cathepsin W-expressing cells was studied in gastrointestinal tissue specimens using the antibody CW-401B1. All
cathepsin W-positive cells had a 'lymphocyte phenotype'. Notably, samples from patients suffering from chronic
inflammatory bowel disease (
Crohn's disease, CD; ulcerative coliltis, UC) or autoimmune
gastritis revealed variable amounts of
cathepsin W-expressing cells. The relative portion of
cathepsin W-positive cells among the infiltrating leukocytes (determined by CD45) differed remarkably. In autoimmune
gastritis,
cathepsin W-expressing cells made up for 65% of all CD45+ cells, whereas the corresponding values for CD and UC were 11% and 6%, respectively. These differences imply a distinct involvement of cytotoxic cells expressing
cathepsin W in the pathogenesis among these diseases. Furthermore, it was tested whether the pro-inflammatory
cytokines TNF-alpha and IFN-gamma can regulate
cathepsin W gene expression in NK-92 cells. Both pro-inflammatory
cytokines had only little effect on the
cathepsin W gene expression of these cells.