Interleukin-6, a growth promoting cytokine, is present in human pituitary adenomas: an immunocytochemical study.

OBJECTIVE: The aim of this study was to investigate the presence of interleukin-6 (IL-6) in human pituitary adenomas. DESIGN: Immunocytochemistry was performed in 15 cases of pituitary adenomas obtained at transsphenoidal surgery. PATIENTS: Fifteen cases of pituitary adenomas were examined; these included five GH-secreting adenomas, four prolactinomas, four ACTH-secreting adenomas and two null-cell ('functionless') adenomas. MEASUREMENTS: Each tumour was stained for the presence of IL-6 by means of the avidin-biotin-peroxidase complex (ABC) technique, and was also stained for GH, prolactin, ACTH and alpha-subunit by conventional immunocytochemistry. RESULTS: Fourteen of the 15 tumours examined, excepting one GH-secreting tumour, demonstrated clusters of IL-6 positively stained cells; the specificity of the staining was established by a significant decrease in staining in parallel sections of all tumours studied when the anti IL-6 antibody was preabsorbed with recombinant human IL-6. CONCLUSIONS: It is concluded that IL-6 immunoreactivity is present in human pituitary tumours, and is independent of the specific secretory cell product. The role of this cytokine in the pathogenesis of such tumours requires further investigation