Flow cytometric staining of pancreatic endocrine cells

Few distinct surface markers have been identified for endocrine cells, but antibodies directed against hormonal epitopes are widely available. In this study, human fetal pancreatic beta cells were identified on the flow cytometer by intracellular staining for insulin. A paraformaldehyde based permeabilization scheme was used which preserves surface staining and helps maintain cell integrity while allowing antibodies access to compartments within the cell interior. Cells were first stained for surface antigens, fixed in paraformaldehyde, and then permeabilized in phosphate buffered saline containing 0.2 percent Tween. Intracellular staining was accomplished using a fluorescein conjugated anti-insulin monoclonal antibody. In this manner, major histocompatibility complex Class II antigen expression was documented on beta cells exposed to interferon gamma. This study demonstrates the feasibility of using hormonal content to identify endocrine cells by flow cytometry while simultaneously staining for surface antigens.