Localization of intrinsic factor and complement fixing intrinsic factor--intrinsic factor antibody complex in parietal cell of man.

In an attempt to localize intrinsic factor in the human parietal cell, and to study its intracellular union with the intrinsic factor antibody and complement, intrinsic factor antibody was separated from coexisting parietal cell antibody in pernicious anaemia sera by gel filtration. Intrinsic factor antibody of both binding' and blocking' type was also produced in rabbits by immunization with semi-purified human intrinsic factor–[Co]B complex. Intrinsic factor antibody obtained from both sources produced fluorescence in the human parietal cells in the indirect Coons' test in the presence of fluoresceinated anti-human IgG. The fluorescence was localized peripherally, at the cell membrane. When instead of the fluoresceinated anti-human IgG a fluoresceinated anti-human complement (C) serum and normal complement containing serum were used, intrinsic factor antibody from both sources produced fluorescence of the entire parietal cell cytoplasm of the human mucosa. Thus, intrinsic factor was localized at highest concentration at the membrane of the parietal cell in man, the intrinsic factor antibody–intrinsic factor complex was demonstrated within the human parietal cell, and evidence was obtained that this antigen–antibody complex fixes complement (C). The possible role of the intrinsic factor–intrinsic factor antibody–complement complex in the development of gastric atrophy in pernicious anaemia has been considered.