Down-regulation of autoantibody levels of cyclosporine and bromocriptine treatment in patients with uveitis

Cyclosporine: A Historical Perspective on Its Role in the Treatment of Noninfectious Uveitis

The history of cyclosporine and uveitis is intertwined with the development of experimental autoimmune uveitis (EAU) animal models and the understanding that T lymphocytes play a major role in the pathogenesis of uveitis. The early studies of CsA in uveitis also demonstrated the power of collaborative efforts in translational research. Dr. Robert Nussenblatt and his colleagues were the first to show that CsA can inhibit EAU. Over many years after the initial CsA experiments, Dr. Nussenblatt's group as well as others continued to study CsA under experimental conditions as well as in clinical trials with human patients. The data and observations from these studies significantly advanced our knowledge of uveitis pathophysiology and demonstrated the value of well-designed masked, controlled treatment trials in uveitis. Dr. Nussenblatt and his collaborators delved into the most significant adverse effect of CsA, renal toxicity, and helped elucidate the pathophysiology of renal injury. They explored adjunctive treatments to improve the efficacy and decrease the toxicity of CsA and also studied other members of the cyclosporine family. Among the immunosuppressives used to treat ocular inflammation, CsA was the first, and remains the only medication comprehensively studied under both experimental and clinical conditions.

Immunomodulatory therapy for ocular inflammatory disease: a basic manual and review of the literature

Corticosteroids are used as first-line treatment for many ocular inflammatory conditions. The risk of adverse effects, however, necessitates conversion to steroid-sparing immunomodulatory therapy (IMT) for disease that is recurrent, chronic, or poorly responsive to treatment. Combination drug treatments with multiple agent 'recipes' are also considered. Immunomodulatory agents include the broad categories of antimetabolites (azathioprine, methotrexate, mycophenolate mofetil), alkylating agents (cyclophosphamide, chlorambucil), T-cell inhibitors (cyclosporine, tacrolimus), and cytokines (interferon alfa). This article reviews and summarizes the evidence for IMT agent use in the treatment of various forms of ocular inflammation.

Hyperactivity in a mouse model of the antiphospholipid syndrome

In the antiphospholipid syndrome (APS), antibodies to a complex of phospholipids and beta2-glycoprotein I (beta2-GPI) are associated with recurrent thromboembolic events, spontaneous abortions, thrombocytopenia and central nervous system (CNS) disturbances. Animals immunized with beta2-GPI develop the systemic manifestations of APS but the involvement of the (CNS) in these animals has not been studied. The objective of the present study was to examine mice with induced experimental APS for behavioral changes. Female Balb/C mice were immunized once with beta2-GPI in complete Freund's adjuvant (CFA) or with CFA alone. Four months after immunization the mice were tested in the staircase apparatus and the following two variables were measured: (1) number of rears: and (2) number of stairs climbed by the mice. Immunization with beta2-GPI resulted in elevated levels of circulating anti-negatively charged phospholipids and anti-beta2-GPI antibodies. The APS mice exhibited hyperactive behavior as reflected by more frequent rears (P < 0.023) and higher number of stairs climbed (P < 0.019) by the mice in 3 min. This simple test demonstrated that experimental APS animals are significantly hyperactive and may serve as a marker for CNS involvement in this model.

Treatment of MRL/lpr mice, a genetic autoimmune model, with the Ras inhibitor, farnesylthiosalicylate (FTS)

Activation and proliferation of lymphocytes requires the active signal transducer Ras. Activation of lymphocytes, associated with autoimmunity, may therefore be modified by S-farnesylthiosalicylic acid (FTS), a synthetic substance that detaches Ras from the inner cell membrane and induces its rapid degradation. The MRL/lpr mouse is a genetic model of a generalized autoimmune disease sharing many features and organ pathology with systemic lupus erythematosus (SLE) and the primary antiphospholipid syndrome (APS). The objective of the present study was to examine the effect of FTS on laboratory and clinical pathology in the MRL/lpr mouse. Female MRL/lpr (n = 50) and MRL/++ control (n = 35) mice were treated intraperitoneally with either FTS (5 mg/kg/day) or saline between 6 and 18 weeks of age. The mice were weighed, tested for proteinuria and lymphadenopathy, lymphocyte proliferation, antibodies, grip strength and behaviour in an open field. FTS treatment resulted in a 50% decrease in splenocyte proliferation to ConA, LPS and a disease specific antigen, beta(2)-glycoprotein-I, and in a significant decrease in serum antibody levels against cardiolipin and dsDNA. Proteinuria and grip strength were normalized and lymphadenopathy and postmortem lymph node and spleen weights were significantly reduced in FTS treated MRL/lpr mice. These findings indicate that modulation of Ras activation has a significant impact on the MRL/lpr model and may represent a new therapeutic approach for the treatment of systemic autoimmune diseases such as SLE and APS.

Autoantibodies specificity in acute anterior uveitis according to the presence of the HLA-B27 allele

PURPOSE

To study HLA-B27(+) and HLA-B27(-) patients with AAU with respect to the frequency and specificity of organ-specific and non-organ-specific autoantibodies.

METHODS

Fifty-seven consecutive patients with AAU were subjected to ophthalmologic and rheumatologic evaluation as well as to autoantibody determination: antinuclear antibodies (ANA), rheumatoid factor (RF), anticardiolipin, anti-smooth muscle, and anti-parietal cell antibodies, and immunoblot for antibodies to HeLa cells and to bovine iris extract. HLA-B27 was determined by a microlymphocytotoxicity assay. Statistical analysis employed chi-square test, Fisher's exact test, and McNemar test.

RESULTS

Thirty-four patients had the HLA-B27 allele (B27(+)/AAU) and 23 did not (B27(-)/AAU). ANA, RF, anticardiolipin, and anti-parietal cell antibodies appeared in low frequency. No patient presented anti-smooth muscle antibody. Immunoblot showed a high frequency of antibodies to HeLa cell proteins in B27(-)/AAU patients with predominant reactivity at 46 kDa and 56 kDa. In contrast, sera from B27(+)/AAU patients reacted poorly against HeLa cell antigens. Immunoblot with bovine iris extract showed a significant frequency of antibodies in both groups, with a predominant response to antigens with an estimated mobility of 35, 52, and 54 kDa.

CONCLUSION

Antibodies specific to iris antigens were equally frequent in both acute uveitis groups, whereas non-organ-specific autoantibodies, especially those to HeLa cell proteins, were far less frequent in B27(+)/AAU than in B27(-)/AAU patients.

Upregulation of lymphocyte apoptosis as a strategy for preventing and treating autoimmune disorders: a role for whole-food vegan diets, fish oil and dopamine agonists

Induced apoptosis of autoreactive T-lymphocyte precursors in the thymus is crucial for the prevention of autoimmune disorders. IGF-I and prolactin, which are lymphocyte growth factors, may have the potential to suppress apoptosis in thymocytes and thus encourage autoimmunity; conversely, dietary fish oil rich in omega-3 fats appears to upregulate apoptosis in lymphocytes. Since whole-food vegan diets may downregulate systemic IGF-I activity, it is proposed that such a diet, in conjunction with fish oil supplementation and treatment with dopamine agonists capable of suppressing prolactin secretion, may have utility for treating and preventing autoimmune disorders. This prediction is consistent with the extreme rarity of autoimmune disorders among sub-Saharan black Africans as long as they followed their traditional quasi-vegan lifestyles, and with recent ecologic studies correlating risks for IDDM and for multiple sclerosis mortality with animal product and/or saturated fat consumption. Moreover, there is evidence that vegan or quasi-vegan diets are useful in the management of rheumatoid arthritis, multiple sclerosis, and possibly SLE. The dopamine agonist bromocryptine exerts anti-inflammatory effects in rodent models of autoimmunity, and there is preliminary evidence that this drug may be clinically useful in several human autoimmune diseases; better tolerated D2-specific agonists such as cabergoline may prove to be more practical for use in therapy. The moderate clinical utility of supplemental fish oil in rheumatoid arthritis and certain other autoimmune disorders is documented. It is not unlikely that extra-thymic anti-inflammatory effects contribute importantly to the clinical utility of vegan diets, bromocryptine, and fish oil in autoimmunity. The favorable impact of low latitude or high altitude on autoimmune risk may be mediated by superior vitamin D status, which is associated with decreased secretion of parathyroid hormone; there are theoretical grounds for suspecting that parathyroid hormone may inhibit apoptosis in thymocytes. Androgens appear to up-regulate thymocyte apoptosis, may be largely responsible for the relative protection from autoimmunity enjoyed by men, and merit further evaluation for the management of autoimmunity in women. It will probably prove more practical to prevent autoimmune disorders than to reverse them once established; a whole-food vegan diet, coupled with fish oil and vitamin D supplementation, may represent a practical strategy for achieving this prevention, while concurrently lowering risk for many other life-threatening 'Western' diseases.

Bromocriptine in rheumatic and autoimmune diseases

BACKGROUND AND OBJECTIVES

Multiple lines of evidence support the concept that the anterior pituitary hormone prolactin has a pathogenic role in rheumatic and autoimmune diseases including, but not limited to, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Reiter's syndrome, psoriatic arthritis, and uveitis. Conversely, the dopaminergic agonist bromocriptine appears to have therapeutic effects through suppression of pituitary prolactin secretion and, perhaps, through actions on peripheral dopamine receptors. This article reviews the experimental and clinical data supporting the therapeutic use of bromocriptine as a nonstandard or adjunctive therapy in rheumatic and autoimmune diseases.

METHODS

Data addressing the potential therapeutic role of bromocriptine in rheumatic and autoimmune diseases, as well as frequently associated comorbidities, was accumulated from the author's work, online literature search of the National Library of Medicine, and references from these identified publications.

RESULTS

There have been a number of clinical therapeutic trials using 2.5 to 30 mg of bromocriptine per day in a single or divided dose, which have shown efficacy with minimal side effects in the treatment of rheumatic and autoimmune diseases. In RA, bromocriptine administration has induced immunosuppression of several immune parameters and has been associated with improvements in morning stiffness, grip strength, numbers of swollen/painful joints, and the Health Assessment Questionnaire disability index. In two blinded studies, bromocriptine reduced the number of SLE flares and was as effective as hydroxychloroquine in reducing lupus disease activity indices, respectively. In case reports, bromocriptine has been used successfully in the treatment of Reiter's syndrome enthesopathy and psoriatic arthritis. The potential efficacy of bromocriptine in the treatment of uveitis and multiple sclerosis is suggested but remains to be verified.

CONCLUSIONS

Double-blind, placebo-controlled studies are limited, but clinical observations and trials support the use of bromocriptine as a nonstandard primary or adjunctive therapy in the treatment of recalcitrant RA, SLE, Reiter's syndrome, and psoriatic arthritis and associated conditions unresponsive to traditional approaches. Additional investigation is needed to verify this conclusion and extend preliminary results.

RELEVANCE

In patients with rheumatic and autoimmune diseases, bromocriptine may be a relatively safe and efficacious alternative therapy. Semin Arthritis Rheum 31:21-32.

Bromocriptine in systemic lupus erythematosus: a double-blind, randomized, placebo-controlled study

The objective of this study was to investigate the efficacy and safety of bromocriptine (BRC) as an adjunct to conventional treatment in systemic lupus erythematosus (SLE). A prospective, double-blind, randomized, placebo-controlled study compared BRC at a fixed daily dosage of 2.5 mg with placebo. Patients were followed for 2-17 months (mean 12.5 months). Disease activity was assessed using the SLE Disease Activity Index (SLEDAI), numbers of flares were recorded, and serum prolactin (PRL) levels were obtained at intervals during the study. Patients were allowed to take prednisone and immunosuppressive drugs. Sixty-six patients with SLE entered the study. Thirty-six were treated with BRC, and 30 controls received placebo. Sixteen patients were removed from the study during the treatment period: five in each group left the study because of adverse effects, five became pregnant, and one patient who took placebo died with central nervous system lupus. Four patients in the BRC treatment group and three patients in the placebo group moved away or stopped coming for study visits for unknown reasons, and were lost to follow-up during the course. At entry, serum PRL was (mean+/-s.d.) 24.8 ng/ml+/-18.4 in the BRC treatment group. This value fell to 5.8+/-9.0 after 12 months of treatment. Corresponding PRL values in controls were 23.7+/-22.1 pretreatment and 20.3+/-14 after 12 months. PRL levels in BRC-treated subjects were significantly lower than levels in control subjects after 3, 6, 9, and 12 months of treatment. The SLEDAI score on the fifth protocol visit was decreased significantly in the BRC group vs controls: 0.9+/-1.4 vs 2.6+/-4.5 (P < 0.05). Although the absolute number of flares in each group was similar, the mean number of flares/patient/month was decreased significantly in the BRC group compared to the control group (0.08+/-0.1 vs 0.18+/-0.2, P = 0.03). Long term treatment with a low dose of BRC appears to be a safe and effective means of decreasing SLE flares in SLE patients.

Anti-endothelial cell antibodies in the sera of hyperprolactinemic women

Prolactin (PRL) is closely associated with autoimmune diseases in animal models and humans, and several disease-related autoantibodies were reported in increased titers in patients with hyperprolactinemia (HPRL). We studied the presence of anti-endothelial cell antibodies (AECA) and other autoantibodies in sera of female patients with HPRL. Sera from 25 HPRL patients and 10 healthy female controls were tested for AECA (against both macrovascular and microvascular endothelial cell antigens), anti-dsDNA, and anti-cardiolipin (anti-CL) using ELISA. Sera were considered positive for the autoantibody when the optical density (OD) value was more than 3 s.d. above the mean of the OD in normal controls. Sera from 13 patients were obtained repeatedly during dopaminergic anti-PRL treatment, to relate PRL level or anti-PRL treatment with the autoantibody levels. Elevated micro and/or macrovascular AECA were observed in sera from 19/25 patients (76%). Elevated titers of anti-CL Abs, all beta2-GPI-dependent, and low levels of anti-dsDNA antibodies (Abs) were also observed in the HPRL patients. Inhibition studies showed that the affinity purified AECAs bound the endothelial cell (EC) antigens in a dose-dependent manner. Titers of AECA as well as anti-DNA and anti-CL autoantibodies did not correlate with PRL level nor with the use or duration of anti-PRL treatment. None of the HPRL patients presented clinical manifestations of autoimmune disease. We conclude that elevated levels of AECA as well as anti-DNA and anti-CL autoantibodies are frequent in hyperprolactinemia. Our results further support the association of PRL and autoimmunity, and may point to a relationship between AECA-associated diseases and HRPL. The presence of autoantibodies in patients with HPRL might portend an increased risk for future development of autoimmune disease.

Cyclosporine monitoring with levels 6 hours after the morning dose in patients with noninfectious uveitis

PURPOSE

The authors evaluate whether monitoring of cyclosporine blood levels 6 hours after the morning dose (T6), as opposed to trough (T0), could reduce the incidence of side effects.

METHODS

Cyclosporine dose adjustments were performed based on blood cyclosporine T6 enzyme-multiplied immunologic technique, irrespective of T0 and serum creatinine (SCr), in eight steroid- or azathioprine-resistant uveitis patients. The cyclosporine dose was adjusted to achieve a cyclosporine T6 level of 150 to 250 ng/ml.

RESULTS

All patients improved clinically over 16 +/- 10 months. The mean dose of cyclosporine was 3.9 +/- 1.4 mg/kg/day. In 149 visits (47%), 70 dose adjustments were made. Initial and final SCr, potassium, magnesium, and uric acid serum levels and systolic/diastolic blood pressure measurements were not statistically different. There was no change in the creatinine clearance, glomerular filtration rate, or the effective renal plasma flow performed before starting T6 monitoring and at 13 +/- 8 months of follow-up.

CONCLUSIONS

Cyclosporine monitoring according to T6 levels is associated with optimal immunosuppression and stable renal function in patients with noninfectious uveitis.

Synergism between long-acting bromocryptine microcapsules and cyclosporine A in the prevention of various autoimmune diseases in rats

Pre-treatment of male Sprague-Dawley rats with long-acting bromocryptine microcapsules (CBLA) significantly inhibited the arthritic response to Freund's complete adjuvant and reduced weight loss, thymolysis, splenomegaly and leukocytosis. In the prevention of adjuvant arthritis (AA), the combination of CBLA plus sub-optimal doses of cyclosporine A (CsA) was more efficient than either of the drugs alone. Sub-optimal doses of CsA were 0.1 and 1.0 mg/kg/day s.c. for 5 days. Furthermore, CBLA alone did not decrease the incidence of experimental allergic uveitis (EAU) in the male Lewis rats. Low-dose CsA reduced the incidence of uveitis by 50%, and with the addition of CBLA, 100% of rats were protected. Low-dose CsA was 2 mg/kg/day i.m. for 14 days. Long-term treatment of male Sprague-Dawley rats with CBLA alone reduced the incidence and severity of spontaneous autoimmune periarteritis nodosa (PN) in a dose-dependent manner; CsA was less potent than CBLA, and only additive effects were obtained. Finally, for the prevention of spontaneous autoimmune insulin-dependent diabetes (DM), the administration of CBLA did not improve the effect of a low-dose CsA in male BB rats. Nevertheless, a delay in onset of DM could be achieved. A sequential therapy using CsA plus CBLA clearly showed beneficial effects. The dose of CsA was 10 mg/kg p.o. 6 days/week for 21 weeks. Compared with Sprague-Dawley or Lewis male rats, BB male rats showed only weak prolactin suppression after the same doses of CBLA. It is suggested that the use of CBLA may be particularly beneficial in autoimmune disorders. The effectiveness of the combination therapy CBLA plus CsA, however, was dependent on the model considered. Various factors could play a role: (1) the different ways of administering CsA (s.c. in AA, i.m. in EAU and PN, oral in DM); (2) strain-dependency in the capacity of CBLA to suppress Prl secretion; and (3) at least in the BB rats, the transient increase of CsA bioavailibility which was possibly induced by CBLA.

Bioactive GH-like immunoglobulins G in active acromegaly: response to long-term treatment with bromocriptine

In acromegaly, certain forms of circulating immunoreactive hGH are not true GH but IgGs which possess GH biological activity (bioactive GH-like IgGs). In this study, we tested the effect of bromocriptine on circulating bioactive GH-like IgGs in an acromegalic woman. Increasing doses of oral bromocriptine (2.5, 5.0 and 7.5 mg/day) were administered (for 2, 8 and 6 months respectively). TRH tests were performed before treatment and at the end of treatment with each dose. The patient was without detectable pituitary or extra-pituitary tumour by magnetic resonance imaging. Her serum contained bioactive GH-like IgGs equivalent to 240 mU/l of hGH and elevated insulin-like growth factor I (IGF-I; 9500 U/l). Basal hGH was 12.8 mU/l and increased to 220 mU/l 15 min after TRH (200 micrograms, i.v.). In addition, in the basal samples of each test we measured total IgGs (radial immunodiffusion), bioactive GH-like IgGs (isolated by Sephadex and protein A affinity chromatography and assayed using the Nb2 cell assay) and IGF-I(RIA). Bromocriptine treatment gradually reduced serum levels of bioactive GH-like IgGs and IGF-I, with significant falls observed first at 10 months of treatment. Bioactive GH-like IgGs were 240, 240, 36.0 and < 0.124 mU/l and IGF-I levels were 9500, 8700, 4000 and 3100 U/l at 0, 2, 10 and 16 months of treatment, respectively. In contrast, IR-hGH response to TRH decreased after 2 months of treatment to 89 mU/l and to 49.2 mU/l at the end of the study while basal IR-hGH remained between 13 and 8.4 mU/l. Basal PRL fell to almost undetectable levels. Bromocriptine treatment decreased the GH response to TRH and the serum concentration of bioactive GH-like IgGs and IGF-I. The striking similarity between the pattern of decrease of serum bioactive GH-like IgGs and IGF-I supports the presence of an immuno component in our patient's acromegaly.

Cellular and humoral immune parameters in women with pathological hyperprolactinemia before and during treatment with bromocriptine

PROBLEM

Experimental and clinical evidence has suggested an immunostimulatory effect of prolactin and that bromocriptine, an inhibitor of prolactin release, counteracts the actions of prolactin on the immune system. The aim of this study was to determine the impact of elevated serum prolactin levels on the immune system in patients with pathological hyperprolactinemia.

METHOD

For this purpose, parameters of the cellular and humoral immune system were studied in six women with prolactinomas and one with idiopathic hyperprolactinemia. Studies were performed when serum prolactin concentrations were high as well as during different phases of the menstrual cycle when prolactin levels had been normalized through treatment with bromocriptine.

RESULTS

Hyperprolactinemic subjects, when compared with six age-matched normal women, had significantly higher percentages of total lymphocytes and CD2+ cells. Elevation of CD4+ cells was also observed although to a lesser extent. Bromocriptine-treated patients, when compared with normal women were characterized by increased numbers of total lymphocytes and CD4+ cells, decreased percentage of CD8+ cells, and increased concentrations of serum IgM. These last two findings were also significantly different when compared to those observed in hyperprolactinemia.

CONCLUSION

In this study we have described the changes on cellular and immune parameters in patients with hyperprolactinemia before and during bromocriptine therapy, which support the links of communications between the immune and endocrine systems in humans.

Immunosuppressive property of bromocriptine on human B lymphocyte function in vitro

Bromocriptine (BRC), a dopamine ergot alkaloid, inhibits the release of pituitary prolactin (PRL). Hypoprolactinaemia induced in rat by treatment with BRC produces a similar immunosuppressive effect as observed in hypophysectomized rats. The effect of immunosuppression by the administration of BRC has been interpreted as the result of hypoprolactinaemia produced by BRC. However, the direct effect of BRC on lymphocyte function has never been evaluated. The purpose of this study was to investigate the in vitro effect of BRC on human B cell functions. Highly purified B cells from tonsil samples were isolated by Percoll density gradient from non-rosetted cells, and were used as target cells. BRC significantly suppressed the proliferative response of resting and activated B cells in vitro. It suppressed immunoglobulin generation of activated B cells. The inhibition of BRC was manifested in the early stage of the proliferation and differentiation of B cells. The conditioned medium from the polyclonal B cell mitogen-stimulated B cell cultures did not contain PRL as detected by immunoradiometric assay. Treatment with low-dose cyclosporin A or FK506 in conjunction with BRC has proved more effective than either drug alone in suppression of B cell proliferation. Thus, the combined therapy of BRC and immunosuppressants may be effective with decreased toxicity for clinical use.

Hormones in self tolerance and autoimmunity: a role in the pathogenesis of rheumatoid arthritis?

Recent studies indicate that pituitary hormones play an important role in immunoregulation. The evidence that endocrine abnormalities are associated with, and may contribute to the development of autoimmune disease is reviewed and discussed. Patients suffering from rheumatoid arthritis show a number of endocrine abnormalities that indicate altered pituitary function. The decreased bioactivity of prolactin and possible inadequate glucocorticoid response to inflammation found in patients may have an etiological role in rheumatoid arthritis. The further clarification of the possible role of endocrine factors in the etiology of autoimmune disease is needed urgently.

The effect of cyclosporin A on early and late stages of experimental lupus

OBJECTIVE

To investigate the effect of cyclosporin A (CSA) on the development of lupus in an experimental model.

METHODS

Lupus was induced in naive mice following injection of a human anti-double-stranded DNA (anti-dsDNA) monoclonal antibody carrying the 16/6 idiotype (Id). CSA was injected into the mice at an early stage of the disease (2 months after immunization) and at a late stage (4 months after immunization).

RESULTS

CSA was found to have a suppressive effect on autoantibody production, as well as on the appearance of other disease manifestations, in the mice with lupus. The effects of the drug were more prominent when the mice were treated at an early stage. This was reflected by a dramatic decrease, to normal levels, in autoantibodies to dsDNA, histones, cardiolipin, Sm, RNP, SS-A/Ro, SS-B/La, and anti-DNA 16/6 Id. Similar effects on the erythrocyte sedimentation rate, white blood cell count, and urinary protein levels were noted. These data were supported by electron microscopy analysis showing a lack of immunoglobulin deposition in the kidneys of mice in which treatment was started early.

CONCLUSION

This study demonstrates that, similar to findings in other autoimmune conditions (e.g., insulin-dependent diabetes mellitus), administration of CSA at an early stage in systemic lupus erythematosus may be more beneficial than if the drug is given at a later stage.

Hyperprolactinemia inhibits natural killer (NK) cell function in vivo and its bromocriptine treatment not only corrects it but makes it more efficient

We studied NK cell function in eight patients with pathological hyperprolactinemia by measuring 51Cr release by K562 cells exposed to their mononuclear cells and found it decreased compared to normal controls (P less than 0.01). Bromocriptine (BrC) treatment corrected NK function but also made it more efficient at 12:1 than at 25:1 or 50:1 effector:target ratios (ANOVA; P = 0.01). The study of NK cell function in agarose revealed that its decrease in hyperprolactinemia is due to their low active binding to target cells, active killing, and recycling capacity. BrC tended to correct them but also increased recycling capacity to levels higher than those of controls (P less than 0.05). Sequential studies in three hyperprolactinemic patients before and after BrC showed correction of NK function within 1 week but its increased efficiency at the 12:1 effector:target ratio required 8 weeks. We conclude that hyperprolactinemia decreases NK cell function. BrC corrects this by decreasing prolactin levels but also makes NK function more efficient by increasing the capacity of NK cells to recycle after killing.

Prolactin, immunoregulation, and autoimmune diseases

Cells of the immune system synthesize prolactin and express mRNA and receptors for that hormone. Interleukin 1, interleukin 6, gamma interferon, tumor necrosis factor, platelet activator factor, and substance P participate in the release of prolactin. This hormone is involved in the pathogenesis of adjuvant arthritis and restores immunocompetence in experimental models. In vitro studies suggest that lymphocytes are an important target tissue for circulating prolactin. Prolactin antibodies inhibit lymphocyte proliferation. Prolactin is comitogenic with concanavalin A and induces interleukin 2 receptors on the surface of lymphocytes. Prolactin stimulates ornithine decarboxylase and activates protein kinase C, which are pivotal enzymes in the differentiation, proliferation, and function of lymphocytes. Cyclosporine A interferes with prolactin binding to its receptors on lymphocytes. Hyperprolactinemia has been found in patients with systemic lupus erythematosus. Fibromyalgia, rheumatoid arthritis, and low back pain patients present a hyperprolactinemic response to thyrotropin-releasing hormone. Experimental autoimmune uveitis, as well as patients with uveitis whether or not associated with spondyloarthropathies, and patients with psoriatic arthritis may respond to bromocriptine treatment. Suppression of circulating prolactin by bromocriptine appears to improve the immunosuppressive effect of cyclosporine A with significantly less toxicity. Prolactin may also be a new marker of rejection in heart-transplant patients. This body of evidence may have an impact in the study of rheumatic disorders, especially connective tissue diseases. A role for prolactin in autoimmune diseases remains to be demonstrated.

The effect of the immunomodulator agent AS101 on interleukin-2 production in systemic lupus erythematosus (SLE) induced in mice by a pathogenic anti-DNA antibody

The role of the synthetic immunomodulator AS101 on the production of interleukin-2 (IL-2) by spleen cells of mice with SLE was investigated. BALB/c female mice, in which SLE was induced by immunization with the pathogenic idiotype of anti-DNA antibody 16/6 Id were treated with AS101 for 7 weeks 2 and 4 months after induction of the disease. The ability of the splenocytes of the mice with SLE to produce IL-2 was restored after administration of AS101. This effect was particularly impressive when the 7-week AS101 treatment was initiated 4 months after immunization. Despite its beneficial effect on IL-2 production, AS101 exerted no influence on the titres of autoantibodies in the sera of the mice. It also had no effect on clinical parameters of SLE, such as the increased sedimentation rate, proteinuria and low white blood cell counts. Our data indicate that defective IL-2 production in SLE is probably secondary to other disease processes and is not necessarily associated with the production of autoantibodies in this disorder.