GROWTH OF RAT PANCREATIC ACINAR-CELLS QUANTITATED WITH A MONOCLONAL-ANTIBODY AGAINST THE PROLIFERATING CELL NUCLEAR ANTIGEN

The monoclonal antibody PC10 raised against the proliferating cell nuc lear antigen (PCNA) was used to study acinar cell replication in the p ancreas of rats under different functional conditions. In Western blot s, the antibody recognized a single band of 37 kDa in pancreatic homog enates indicating its specificity in this particular species and organ . Three conditions of growth were chosen for immunohistochemical analy sis: pancreatic pre-and postnatal development, pancreatic regeneration after injury, and cholecystokinin-stimulated acinar cell proliferatio n. The time course of acinar cell replication under each condition was the same as that obtained after tritiated thymidine incorporation wit h subsequent autoradiography, indicating that the percentage of PCNA-p ositive cells reflects the pool of cycling cells in the models investi gated. However, the absolute number of PCNA-positive cells was two to ten times higher than comparable labeling indices from H-3-thymidine a utoradiography. This finding might reflect the half life of PCNA, whic h exceeds the duration of the S-phase. Thus, PCNA-positive cells not o nly represent S-phase cells, but also cells that have recently complet ed the cell cycle.