AMYLOID DEPOSITS IN PITUITARIES AND PITUITARY-ADENOMAS - IMMUNOHISTOCHEMISTRY AND IN-SITU HYBRIDIZATION

The patterns of deposition and immunoreactivity of interstitial amyloi d were studied in 11 pituitary glands obtained at autopsy and 9 surgic ally resected pituitary adenomas using Congo red staining and a panel of antisera directed against 5 major amyloid fibril proteins and all p ituitary hormones. The deposition pattern of amyloid in pituitary glan ds differed from that in adenomas but all amyloid deposits showed an i mmunostaining with anti-amyloid lambda-light chain. The remaining anti sera were immunonegative, In situ hybridization using an oligodeoxyrib onucleotide-probe complementary to the mRNA coding for the constant re gion of human lambda-light chain yielded no hybridization signals in t he pituitaries or pituitary adenomas, excluding loca I synthesis and s ecretion of immunoglobulins, Since no case studied suffered from gener alized A lambda-amyloidosis and adsorption of immunoglobulins to the u nknown amyloid fribril protein of the pituitary seems to be unlikely, crossreaction of the polyclonal antisera with an undefined antigen is probable. The similar immunostaining properties of amyloid deposits in ''normal'' pituitaries and pituitary adenomas suggest they both origi nate from the same precursor protein.