Hormone release by islet B cell-enriched and A and D cell-enriched populations prepared by flow cytometry

Dispersed pancreatic islet cells were analyzed for their low forward angle light scatter using flow cytometry. The cells produced a distinct light scatter pattern which appeared to be a function of cell size and not cell granularity. RIA of hormone content of cells collected from different regions of the pattern revealed that glucagon- and somatostatin-containing cells were concentrated in regions of lower scatter intensity and that insulin-containing cells were more numerous in regions of higher intensity. Relative to the original cell suspension, these preparations were enriched 3-fold in glucagon and somatostatin content and 6-fold in insulin content. The function of intact islets, unsorted dispersed cells, and sorted dispersed cells was examined before and after 4 days of culture. Before culture, all of the dispersed cell populations had elevated basal secretion compared with intact islets and did not respond to stimulatory concentrations of glucose, arginine, or 3-isobutyl-1-methylxanthine. After culture for 4 days, basal secretion fell, and responsiveness returned. In both the A/D cell-enriched and the B cell-enriched cultured populations, the percentage of single cells was approximately 95%. The insulin release patterns from these populations were similar to those from intact islets and unsorted dispersed cells. Glucagon release from all of the dispersed cell populations far exceeded that from intact islets. This study suggests that the structural organization of islets influences A cell function, but a clear influence upon B cell function has not been demonstrated.