Immunocytochemical localization of soluble protein in the adrenal medulla

Synopsis An indirect immunocytochemical technique (Nakane, 1970) was employed to localize the soluble proteins purified from lysates of catecholamine (CA)-containing vesicles of the bovine adrenal medulla. Antiserum to the proteins, produced in rabbits, was used for incubation of sections of bovine adrenal tissue prepared by fixation in glutaraldehyde and embedding in serum albumin (McLean & Singer, 1970). The site of the antigen-antibody complex was visualized by incubating the sections with anti-rabbit -globulin (goat) conjugated to peroxidase, followed by the deposition of electronopaque reaction product generated by the enzyme. The reaction product, also visible at the level of the light microscope, appeared to have a distribution similar to that of the CA-storage vesicles. Electron microscopic examination revealed that nearly all the reaction product was deposited over the electron-opaque core of the vesicles. The intravesicular localization is consistent with the proposal that these proteins exist primarily in the CA-containing granular vesicle and may function to stabilize the CA-storage complex.