Immunological studies on the occurrence and properties of chromogranin A and B and secretogranin II in endocrine tumors

We investigated a variety of endocrine tumors for the presence of chromogranins A and B and secretogranin II. These antigens were identified by one- and two-dimensional immunoblotting and in some cases by immunohistochemistry. An antigen corresponding in electrophoretic behavior to adrenal chromogranin A was present in all types of tumors, including insulinomas, oat cell carcinomas, and Merkel cell tumors of the skin. Chromogranin B had a much more limited distribution. This antigen could not be detected in parathyroid adenomas, oat cell carcinomas, or Merkel cell tumors, either by immunoblotting and immunohistochemistry. The occurrence of secretogranin II was similar to that of chromogranin B, with the exception of a positive reaction in Merkel cell tumors. In benign pheochromocytomas, all three antigens were found consistently; whereas in two of three malignant pheochromocytomas, chromogranin B was absent. Our study establishes that in most cases chromogranins and secretogranin in tumors are identical to the adrenal antigens, but that these antigens are not always stored together. Chromogranin A is the most widely distributed marker for endocrine tumors.