Fluorescence microscopic studies and flow cytometric measurements of lectin and hormone binding to isolated rat pancreatic acinar cells.

The binding of fluorescence-labelled lectins and a fluorescence-marked hormone to the cell surface of isolated rat pancreatic acinar cells was studied by light microscopy and flow cytometric measurements. The pancreatic acinar cells were prepared by collagenase digestion. The fluorescence of cells was studied after binding of FITC-labelled WGA or UEA I as well as of FITC-marked pancreocymin/cholecystokinin (CCK-FITC) in a fluorescence microscope or FACScan. The strong binding of lectins was inhibited by preabsorption with the specific sugars. In comparison to the lectins the binding of CCK-FITC was low. There were two populations of acinar cells with different CCK-FITC binding capacity as detected by flow cytometry. The CCK-FITC cell surface fluorescence was significantly decreased by preincubation with unmarked hormone as well as with the non-labelled lectins. The inhibition of CCK-FITC binding by lectins is discussed in respect to a possible competition of the lectins and CCK for the CCK receptor.