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Cellular autoimmunity predicted poor clinical outcome in patients with pituitary adenomas
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Patients with pituitary adenomas had a greater prevalence of serum pituitary antibodies and tumor-infiltrating lymphocytes compared with healthy controls, and presence was associated with a less satisfactory clinical outcome during follow-up.
“This study establishes a positive correlation between pituitary cell-mediated autoimmunity and adenoma disease progression,” researchers in Italy wrote. “Based on our findings, pituitary adenomas seem to be an intermediate condition that holds between normal pituitary and hypophysitis.”
The researchers analyzed the prevalence of pituitary antibodies using immunofluorescence in patients with pituitary adenomas (n=291), healthy controls (n=409) and controls with autoimmune hypophysitis (n=14). For the second part of the study, researchers analyzed a subset of 72 patients who had operated pituitary adenomas using CD45 staining to assess the prevalence of tumor-infiltrating lymphocytes and pituitary antibodies and the correlation with clinical outcome of disease.
The prevalence of serum pituitary antibodies was higher in adenomas (5.2%) compared with healthy controls (0.7%; P<.0001) and lower compared with patients with autoimmune hypophysitis (57.1%; P<.0001).
Researchers observed a similar, higher prevalence of tumor-infiltrating lymphocytes in pituitary adenomas compared with healthy controls (P=.01) and a lower prevalence compared with patients with autoimmune hypophysitis (P<.0001).
The researchers reported no correlation between serum pituitary antibodies and tumor-infiltrating lymphocytes (P=.78).
Poor clinical outcome was more common among patients with pituitary adenoma and tumor-infiltrating lymphocytes (61%) compared with those without (31%; P=.026).
Further, the presence of tumor-infiltrating lymphocytes was an independent prognostic factor for persistence or recurrence of pituitary adenoma, according to multivariate regression analysis.
When the researchers performed a meta-analysis of the present study and 13 previously published studies, the odds of having serum pituitary antibodies were sevenfold greater for patients with pituitary adenoma compared with healthy controls (95% CI, 4.9-11.6).
“Autoantibodies are a classic marker of autoimmune diseases and are of great help for the diagnosis, prediction and, to some extent, monitoring of the remission of the disease,” the researchers wrote.
However, few data are available for tumor-infiltrating lymphocytes in pituitary adenomas, they said.
“Our data well support the hypothesis that pituitary adenomas act as other tumors in predisposing to autoimmunity development,” the researchers concluded. “Our findings need further investigations, such as the analysis of the immune cell subtypes to determine the mononuclear cell types that influence tumor progression.”
Lupi I. J Clin Endocrinol Metab. 2010;95:289–296.