Human gastric intrinsic factor expression is not restricted to parietal cells

Area of Science:

• Gastroenterology
• Cell Biology
• Histology

Background:

• Gastric parietal cells were traditionally considered the exclusive source of intrinsic factor (IF) in humans.
• In animal models, IF has been found in various foregut-derived cells, including chief and enteroendocrine cells.

Purpose of the Study:

• To re-examine the distribution and subcellular localization of intrinsic factor in the human stomach using a novel recombinant human intrinsic factor antiserum.
• To investigate potential non-parietal cell production of intrinsic factor.

Main Methods:

• Immunolight and immunoelectron microscopy were employed to detect intrinsic factor.
• High-titer, monospecific antiserum against recombinant human intrinsic factor was utilized.
• Specificity was confirmed by preabsorption with purified intrinsic factor.

Main Results:

• While most intrinsic factor was found in parietal cells, positive staining was also observed in gastric chief cells and enteroendocrine cells at anatomical region margins (cardia/fundus, body/antrum).
• Subcellular localization included endocytic and apical membranes of parietal cells, secretory granules of chief and enteroendocrine cells, and capillary endothelial cells.
• Specific labeling was confirmed through antibody preabsorption.

Conclusions:

• Human intrinsic factor expression is not limited to parietal cells, with non-parietal cells also demonstrating potential for production.
• The localization of intrinsic factor in non-parietal cells at gastric region margins suggests that local factors may regulate its expression.