Ultrastructural immunocytochemical localization of lysozyme in the Paneth cells of man

Abstract

Human lysozyme was localized immunocytochemically at the ultrastructural level within Paneth cells of man by use of the unlabeled antibody enzyme method. Specific staining for lysozyme was observed over secretion granules in the apical cytoplasm, within the region of the Golgi apparatus and within some, but not all, lysosomes. No staining was observed within the cisternae of the rough endoplasmic reticulum or other cellular organelles. In control experiments comparing semiadjacent sections of the same Paneth cell, substitution of either normal rabbit serum for rabbit antihuman lysozyme antiserum (specificity control) or normal sheep serum for sheep antirabbit immunoglobulin G antiserum (method control) completely eliminated specific staining for lysozyme. The intensity of staining for lysozyme was related to both the titer and length of exposure to antilysozyme antiserum. Specific staining was obtained in tissue embedded in Araldite or Epon and was facilitated by etching with hydrogen peroxide. No staining was observed after prolonged fixation in glutaraldehyde or treatment with uranyl acetate in block.