Immunohistological localization of trypsin in mucus-secreting cell layers of Atlantic salmon, Salmo salar L.

Abstract. Immunohistochcmical examination showed that trypsin was present in mucus-secreting cell layers of Atlantic salmon, such as surface epithelial cells of gills and intestine, and epidermal cells of dorsal skin. Trypsin in tissue slices was identified by an immunohisto-chemical technique which used affinity purified immunoglobulins from rabbit antisera against purified salmon pancreatic trypsin as primary antibodies. Most of the positively stained cells appeared to be granulated and secretory. The authors hypothesize that trypsin in mucus-secreting cell layers is a part of the non-specific immune defence of the fish.