A chromogranin peptide is co-stored with insulin in the human pancreatic islet B-cell granules.
The immunoreaction of a rabbit chromogranin A and B antiserum was studied in normal human pancreatic islets. By examination of consecutive light microscopical sections, it was revealed that, at high antiserum concentrations (1:2000 or less), the whole islet area was heavily labelled, although the peripheral glucagon (A)-cells were the most intense in their immunoreaction. At low antiserum concentrations (1:4000 or more) the A-cells still showed the same intense labelling reaction, but the central B-cells were weakly labelled. Electron microscopically, reactivity towards the chromogranin A and B antiserum and the monoclonal insulin antibodies was present in the same central electron-dense core of the B-cell secretory granules, as demonstrated after application of the immunogold technique at different antibody dilutions. In the A-cells, the chromogranin immunoreactivity was concentrated at the peripheral mantle of the secretory granules. The D-cell granules showed a weak immunolabelling. Examination of human islets with the monoclonal chromogranin A antibody LK2H10 revealed immunogold labelling only in the peripheral mantle of the A-cell granules, while the B-cell granules were unlabelled. The present results show that a chromogranin peptide is co-stored with insulin the in normal human B-cell secretory granules. Although the exact composition of this B-cell chromogranin is unknown, it is not identical to that of the chromogranin A present in the A-cell granules.
Lukinius
A
A
Department of Pathology, University Hospital, Uppsala, Sweden.
Wilander
E
E
Eriksson
B
B
Oberg
K
K
D000328:Adult; D000818:Animals; D053379:Chromogranin A; D002864:Chromogranins / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007106:Immune Sera; D007150:Immunohistochemistry; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010455:Peptides / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D011817:Rabbits
D053379:Chromogranin A; D002864:Chromogranins; D007106:Immune Sera; D007328:Insulin; D010455:Peptides