EXPRESSION OF CHROMOGRANIN-A AND CHROMOGRANIN-B AND SECRETONEURIN IMMUNOREACTIVITY IN NEOPLASTIC AND NONNEOPLASTIC PANCREATIC ALPHA-CELLS

In the endocrine pancreas, chromogranins A and B as well as secretoneu rin (a biologically active peptide processed endoproteolytically from secretogranin II) are most intensely expressed in alpha (glucagon) cel ls. We examined whether the functional status of neoplastic and nonneo plastic human alpha cells is reflected in the expression patterns of c hromogranins/secretogranins. Neoplastic alpha cells were analysed immu nocytochemically in six functioning glucagonomas and 37 nonfunctioning neuroendocrine tumours (29 with alpha cells) for their immunoreactivi ty to chromogranin A and B, as well as secretoneurin. There was no dif ference in the staining intensity for either peptide between glucagono mas and nonfunctioning, alpha cell containing tumours. Nonneoplastic a lpha cells from patients with a functioning glucagonoma showed a decre ased glucagon immunoreactivity, whereas the expression of chromogranin A (but not chromogranin B and secretoneurin) was as intense as in alp ha cells not associated with glucagonoma syndrome. These results sugge st that the expression of chrome granins/secretogranins in neoplastic alpha cells of the pancreas may be independently regulated from the ce lls' functional status. In nonneoplastic alpha cells there seems to be an association between glucagon production and chromogranin B and sec retoneurin expression.