Immunocytochemical localization of macrophage migration inhibitory factor in human hypophysis and pituitary adenomas.

Abstract

To establish the presence of macrophage migration inhibitory factor (MIF) in human nontumorous and adenomatous pituitaries. Macrophage migration inhibitory factor was demonstrated by immunocytochemistry on paraffin sections with a polyclonal antirecombinant murine MIF using the streptavidin-biotin-peroxidase complex method. Nontumorous hypophyses (14 cases) obtained from autopsy and 54 surgically removed pituitary adenomas were studied. In nontumorous pituitaries, serial sections were immunostained for both pituitary hormones and MIF. Macrophage migration inhibitory factor was localized in all corticotrophs, including basophils extending into the posterior lobe, Crooke's cells, and a few thyrotrophs. The posterior lobe was immunonegative for MIF. Densely (five cases) and sparsely (six cases) granulated somatotroph and lactotroph (six cases) adenomas lacked MIF immunostaining. Macrophage migration inhibitory factor was found in 3 of 4 thyrotroph adenomas, 3 of 6 gonadotroph adenomas, 10 of 11 functioning corticotroph and 8 of 10 silent corticotroph adenomas, 3 of 3 null cell adenomas, and 3 of 3 oncocytic adenomas. The immunopositivity was diffuse or focal, and the intensity was variable. This study is the first to demonstrate the presence of MIF in human nontumorous and adenomatous pituitaries using an immunocytochemical staining technique.