In recent years the literature has contained increasing evidence that pituitary hormones are capable of regulating the immune system. There is evidence to suggest that prolactin is an immunostimulatory hormone and that reduction of serum prolactin levels in experimental animals by hypophysectomy or treatment with bromocriptine will result in a degree of immunosuppression. This information has been applied to humans, and two clinical studies have begun. Both are in early phases of patient recruitment. One study is a randomized trial comparing placebo and bromocriptine in recurrent anterior uveitis. Using as outcome the number of recurrences per year, the study will determine whether bromocriptine is capable of regulating the immune system in these patients. The second trial focuses on the additive effects of cyclosporine plus bromocriptine in attempts to treat patients with posterior uveitis at lower doses of cyclosporine to reduce renal toxicity while achieving immunosuppression. Cyclosporine and prolactin compete for binding sites on the lymphocyte. Further studies wt be designed to elucidate other aspects of the neuroendocrine axis that may be used to regulate the immune system in the treatment of autoimmune diseases.
