[Symptomatic glial cysts of the pineal gland: report of two cases and review of the literature]

Referring to two individual cases, the authors review clinical, radiological and histological features of benign glial cysts of the pineal gland. Both patients were young females with aggravating headaches and with convulsions in one case. Symptoms were referable to a space-occupying cystic mass of the pineal gland. On histology, both lesions proved to be non neoplastic cysts without an epithelial lining. Their histogenesis and low growth potential were reinforced by immunohistochemical analysis of pineal antigens and proliferation markers. Glial cysts of the pineal gland are not infrequent, but symptomatic occurrences are exceptional. Most glial cysts are of dysontogenic or degenerative origin. Sometimes, however, the role of hormonal influences or paraneoplastic factors must be considered. Symptoms caused by glial cysts of the pineal gland are non-specific and radiologic imaging technics may contribute little to etiologic diagnosis. Pineal cysts are curable by surgical resection or stereotactic decompression. Whatever the diagnostic approach, emphasis must be laid on the histologic examination in order to avoid unnecessarily aggressive treatment.

The immuno-reconstituting effect of melatonin or pineal grafting and its relation to zinc pool in aging mice

It has been demonstrated that melatonin, the main neuro-hormone of the pineal gland, affects thymic functions and the regulation of the immune system. In addition, experimental evidences indicate that melatonin can modulate zinc turnover. The knowledge that with advancing age both melatonin and zinc plasma levels decline, and that zinc supplementation in old mice is able to restore the reduced immunological functions, has prompted investigations on the effect of chronic melatonin treatment or pineal graft in old mice on the age-related decline of thymic endocrine activity, peripheral immune functions and zinc turnover. Both melatonin treatment in old mice and pineal graft into the thymus of old mice correct the reduced thymic endocrine activity and increase the weight of the thymus and its cellularity. A restoration of cortical thymic volume, as detected by the percentage of tissue in active proliferation, is also observed in old mice after both treatments. Thymocyte CD phenotype expression is also restored to young values. At peripheral level, recovery of peripheral blood lymphocyte number and of spleen cell subsets, with increased mitogen responsiveness also occurs. Melatonin treatment or pineal graft induce also a restoration of the altered zinc turnover in aged mice with an increment of the crude zinc balance from negative (-1.6 microgram/day/mouse) to positive value (+1.2 microgram/day/mouse), similar to that one of young mice (+1.4 microgram/day/mouse). The reduced zinc plasma level is restored to normal values. These findings support the idea that the effect of melatonin on thymic endocrine activity and peripheral immune functions may be mediated by the zinc pool.

Circadian variations of neuropeptide Y-like immunoreactivity in the rat pineal gland

Neuropeptide Y, which is present in the sympathetic nerves innervating pineal glands, has been shown to affect N-acetyltransferase activity and melatonin production. Using enzyme immunoassay, we measured daily patterns of neuropeptide Y (NPY) in rat pineal glands in light-dark cycles (LD) and in constant darkness (DD). NPY within rat pineal glands displayed daily rhythms in LD with a peak at zeitgeber time 16. Similar rhythms in the NPY content were also observed in DD. These rhythms have a similar phase-relationship to that of the rhythm of NAT activity, suggesting that NPY in rat pineal glands plays a role in circadian rhythms of NAT activity.

Effect of pinealectomy upon the nonspecific immune response of the ring-dove (Streptopelia risoria)

The different stages of the phagocytic process by granulocytes of pinealectomized or sham-pinealectomized ring doves (Streptopelia risoria) as well as hematological parameters (total white blood cells, smear, and total protein) and serum hormone levels (triiodothyronine (T3), thyroxine (T4), and corticosterone) were studied. A number of immunological parameters of the phagocytosis process, including adherence capacity, mobility rate, the phagocytosis capacity for inert particles and the digestion capacity of ingested material, were studied. Adult male ring doves were injected intravenously with either 0.1 ml of normal sheep serum (NSS) or saline (SS). Blood samples were collected before injection, and 1 hr, 3 hr, 24 hr, and 4 days afterwards. The results indicate that pinealectomy produces a significant increase in the number of total white blood cells and total protein concentration in plasma in addition to altering different stages of the phagocytic process. During the immunization study, a decrease in the percentage of leukocytes and lymphocytes and an increase in the percentage of heterophils accompanied by an increase in the concentration of serum corticosterone were observed 3 hr following treatment. For the immunological parameters, adherence capacity and latex bead ingestion were increased 3 hr after NSS injection and the NBT reduction test 3 and 24 hr after NSS treatment. In addition, the administration of NSS produced a significant increase in serum T3 and T4 concentrations 4 days following injection. These results show that pinealectomy has a marked effect on both the number and function of immune cells.

Brain-applied magnetic fields and immune response: role of the pineal gland

In an attempt to clarify the mechanisms underlying immunopotentiation induced by prolonged exposure of the rat brain to static magnetic fields, and to evaluate the role of the pineal gland in that phenomenon, experiments were carried out on the following groups of adult rats (maintained under a 12 hr light/12 hr dark photoperiod): pinealectomized rats (Px); rats with micromagnets implanted to the occipito-parietal region of the skull (M); rats pinealectomized and implanted with micromagnets to the skull (PxM); sham-pinealectomized rats with non-magnetic beads implanted to the occipito-parietal area of the skull (ShPxMx); and intact controls (IC). Twenty-one days after surgery, animals of all groups were immunized with sheep red blood cells and tested for plaque forming cell (PFC) response and serum hemagglutinin level. Humoral immune reactions decreased significantly in Px rats, while increased markedly in M rats in comparison to the ShPxMx and IC controls. Compromised immune function induced by pinealectomy was restored by prolonged exposure of the brain to magnetic fields (PxM rats). Thus reconstituted immune responsiveness in PxM rats reached the level observed in controls, but was lower than that in M rats. The results imply that magnetic fields applied to the rat brain may exert their immunoenhancing activity in the absence of the pineal gland. However, this activity of magnetic fields is more pronounced in the presence of the pineal organ. The latter finding suggests the involvement of the pineal in the immunopotentiation induced by magnetic fields, but does not imply that magnetic fields operate solely via the pineal gland.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical and electron-microscopic characterization of macrophage/microglia cells and expression of class II major histocompatibility complex in the pineal gland of the rat

Interstitial cells in the pineal gland of the rat were characterized immunocytochemically using the monoclonal antibodies MRC OX-42 and ED1 for macrophages/microglia, and MRC OX-6, which recognizes major histocompatibility complex (MHC) class II antigen. A polyclonal antibody against GFAP was used to identify astrocytes. Cells immunopositive for OX-42 and/or ED1 were distributed throughout the gland; they extended processes primarily along the perivascular spaces and occasionally within the parenchyma of the gland. Ultrastructurally, these OX-42-positive cells were characterized by a nucleus with sparse heterochromatin and cytoplasmic vacuoles/lysosomes. Cells expressing MHC class II antigen had a distribution and morphology similar to OX-42-immunopositive cells, suggesting that pineal macrophages/microglia play a role as antigen-presenting cells. GFAP-positive astrocytes were concentrated at the proximal end of the pineal where the pineal stalk enters the gland. The occurrence of antigen-presenting cells in this circumventricular neuroendocrine gland has important functional implications as these cells may be mediators of neuroimmunomodulatory mechanisms, and involved in certain disease states such as autoimmune pinealitis.

Melatonin increases antigen presentation and amplifies specific and non specific signals for T-cell proliferation

Our preceding results have shown that melatonin administration to normal and immunodepressed mice increases significantly the antibody response. We also found that melatonin is able to restore the impaired T-helper cell activity in immunodepressed mice. The present study shows that melatonin enhances antigen presentation by splenic macrophages to T-cells. This effect is concomitant with an increase in the expression of MHC class II molecules and production of IL-1 and TNF-alpha. Considering the role of antigen presentation and cytokine production in the initiation of the immune response, the present findings provide evidence for relevant mechanisms that may account for the regulatory role of the pineal gland in immunoregulation.

The immunoneuroendocrine role of melatonin

A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MIIO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as gamma-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.

Experimental autoimmune pinealitis in the rat: ultrastructure and quantitative immunocytochemical characterization of mononuclear infiltrate and MHC class II expression

Lewis rats immunized with Peptide M (an oligopeptide epitope of the S-antigen protein) developed experimental autoimmune uveoretinitis (EAU) and experimental autoimmune pinealitis (EAP). Temporal changes in mononuclear infiltrate to the pineal gland were quantitated by computer image analysis of sections immunostained with monoclonal antibodies to specific mononuclear populations. T helper/inducer cells (W3/25+) and monocyte/macrophages (OX-42+) were elevated during the early phases of inflammation (day 15) while cytotoxic/suppressor T cells (OX-8+) were elevated at days 15 and 21. Expression of MHC class II (OX-6) was markedly enhanced on pineal glia, but was not present on vascular endothelia during EAP. Ultrastructurally, many capillaries exhibited thickenings of the endothelia and basal lamina. EAP had little effect on the fine structure of pinealocytes and glia and there was little evidence of cellular destruction by day 21, in contrast to the extensive retinal destruction resulting from EAU. These findings suggest fundamental differences between EAU and EAP related to mechanisms of antigen processing/recognition in autoimmune diseases. Our study further indicates the importance of EAP as a model to investigate neuroendocrine-immune interactions.

The wavelength of light governing intraocular immune reactions

Injection of antigen into the anterior chamber of the eye results in the induction of suppressed systemic cell-mediated responses as measured by delayed-type hypersensitivity or contact hypersensitivity (CHS). Previous studies from the author's laboratories have determined that this response is governed by exposure of the eye to visible light during the initial intraocular encounter between T cells and antigen. To more fully understand the role of light, as well as to begin to understand the molecular mediators involved, the authors chose to explore the properties of light governing the effect. Neutral density filter were used to demonstrate that the minimum amount of light required to induce suppression of CHS following anterior chamber injection of antigen is 1-2 lux (lumens/meter2). With narrow band filters, the wavelengths responsible for suppression were shown to be 500-510 nm. The results show that the effect of light extends beyond the hapten-derivatized spleen cell system to other antigens placed in the anterior chamber of the eye. Studies also show that the retina and the pineal gland, two light absorbing structures, may not be involved. The results in this report show that light of very restricted wavelengths controls intraocular immune reactions.

Inhibition of experimental autoimmune uveitis by retinal photoreceptor antigens coupled to spleen cells

Experimental autoimmune uveitis (EAU) and experimental autoimmune pinealitis (EAP) are CD4+ T cell-mediated inflammatory diseases of the uveal tract and retina of the eye and of the pineal gland. EAU and EAP can be induced by several retinal autoantigens including S-antigen (S-Ag) and interphotoreceptor retinoid binding protein (IRBP). In this study we investigated the effect of intravenous administration of S-Ag and IRBP coupled to syngeneic spleen cells on the development of EAU and EAP. Injection of S-Ag or IRBP coupled to spleen cells 5 days prior to immunization with native S-Ag or IRBP, respectively, was effective in preventing the induction of EAU and EAP in LEW rats. Conversely, LEW rats receiving S-Ag-coupled spleen cells and challenged with IRBP or LEW rats receiving IRBP-coupled spleen cells and challenged with S-Ag developed a severe EAU within 10 days to 2 weeks following immunization, as did all control animals receiving sham-coupled spleen cells and challenged with the two retinal antigens. The results show that the administration of retinal autoantigens coupled to spleen cells effectively protects against the development of EAU when animals are subsequently challenged with the tolerizing antigen but not when challenged with another unrelated pathogenic retinal autoantigen.

Immunopathology of experimental autoimmune uveoretinitis in primates

The eyes and pineal glands from 10 monkeys immunized with S-antigen were studied using routine histopathological and immunohistochemical techniques. Seven out of 10 animals developed uveitis between 19 and 33 days after the initial immunization. Histopathology of the eyes harvested 70 days after immunization showed moderate to marked uveoretinitis, subretinal fibrosis, retinal necrosis and gliosis. The pineal glands demonstrated chronic pinealitis. The infiltrating cells were both CD3 and CD19/CD22 lymphocytes with a ratio of 1.4 in the eye and 2.2 in the pineal gland. The ratio of CD4 to CD8 lymphocytes was 1.5:1. MHC Class II antigens and adhesion molecule (ICAM-1) were observed on resident cells. The influx of B lymphocytes and the formation of subretinal fibrosis differentiate the disease in the monkey from that in the rat and mouse. These findings are similar to Vogt-Koyanagi-Harada syndrome and subretinal fibrosis with uveitis syndrome in human.

The involvement of pineal gland and melatonin in immunity and aging: II. Thyrotropin-releasing hormone and melatonin forestall involution and promote reconstitution of the thymus in anterior hypothalamic area (AHA)-lesioned mice

A stereotactic electrolytic lesion of the anterior hypothalamic area in mice produces a rapid involution of the thymus and a reduction of lymphocytes in the peripheral blood. This effect on the thymus and blood lymphoid compartment can be prevented by postoperational administration of thyrotropin-releasing hormone (TRH) or melatonin. These activities of TRH or melatonin are antagonized by the opioid receptor blocker naltrexone. They do not seem to depend on stimulation of the thyroid gland or of the endogenous opioid system but rather on a direct activity of TRH on thymic targets or binding sites on lymphocytes.

Pinealitis coincident with recurrent uveitis: immunohistochemical studies

Although experimental models of autoimmune uveitis predict pinealitis coincident with uveitis, there is no direct evidence of pineal pathology accompanying a human uveitis. Horses with naturally occurring uveitis are a potential source of eye and pineal tissues that are not available from human patients with active uveitis. We have observed pinealitis in a mare with equine recurrent uveitis. By immunohistochemistry we demonstrated immunoglobulin and MHC Class II antigen on infiltrating and resident cells of eye and pineal gland. These results support the relevance of the animal models and suggest that pinealitis may be coincident with some human uveitides.

A brief survey of pineal gland-immune system interrelationships

The present paper summarizes evidence that support the hypothesis of the existence of bilateral interactions between pineal gland and the immune system. Both in vivo and in vitro experiments show that the pineal gland, via its hormone melatonin, enhances immune function. Mechanisms involved in this immunostimulatory effect are not well understood, but some evidence suggests the existence of specific binding sites for melatonin on immune cells. Moreover, the release of opioid peptides and interleukin-2 by T-helper cells may also participate in this mechanism by activating, at least natural killer activity and antibody-dependent cellular cytotoxicity. Some immune signals, i.e., gamma-interferon, may be involved in regulating pineal function, thereby representing a regulatory mechanism in the opposite direction. The physiological and clinical significance of these data remains to be studied.

Induction of experimental autoimmune uveitis by the retinal photoreceptor cell protein, phosducin

Experimental autoimmune uveitis (EAU) and experimental autoimmune pinealitis (EAP) are CD4+ T cell mediated inflammatory diseases of the retina and uveal tract of the eye and the pineal gland respectively. They can be induced in experimental animals by immunization with several well characterized retinal autoantigens. We induced a mild to moderate EAU and EAP in Lewis rats by immunization with phosducin, a 33K retinal phosphoprotein which is involved in the phototransduction of vision. In contrast to the severe EAU induced by other retinal antigens like S-antigen (SAg) or interstitial retinoid binding protein (IRBP), the clinical disease was late in onset, low grade in severity and predominantly affected the posterior segment of the eye. Our study demonstrates that another photoreceptor cell protein, phosducin, is capable of eliciting EAU and EAP.

The pineal gland and the clinical course of multiple sclerosis

Clinical, epidemiological, biochemical, immunological, and radiological studies suggest that the pineal gland may be implicated in the pathophysiology of multiple sclerosis (MS). The following communication is concerned with the association among MS, pregnancy, the postpartum period, and melatonin secretion and illustrates, based on a clinical case report, the influence of the pineal gland on the clinical course of MS. This association is noteworthy since MS may worsen during the postpartum period and melatonin secretion is reported to be altered most dramatically by pregnancy and delivery. Since melatonin secretion is cyclical, undergoing diurnal, weekly, seasonal, and annual variations, it is proposed that the pineal gland may be the "prime mover" underlying the spontaneous exacerbations and remissions in MS.

Expression of S-antigen in retina, pineal gland, lens, and brain is directed by 5'-flanking sequences

S-antigen (S-Ag) is an abundant protein of the retina and pineal gland that elicits experimental autoimmune uveitis and pinealocytis in several animal species. To study the elements regulating the expression of S-Ag, we generated transgenic mice expressing the chloramphenicol acetyl transferase (CAT) gene under the control of a 1.3-kilobase pair 5'-flanking segment of the mouse S-Ag gene. While all of the transgenic mice expressed CAT activity in the retina, in some animals CAT activity was also detected in the pineal gland, lens, and brain. Immunoblotting, polymerase chain reaction-mediated detection of RNA, and immunocyto-staining of transgenic tissues with antibodies to CAT and S-Ag established that the profile of expression of the transgene corresponded to that of S-Ag; both proteins were detectable in retinal photoreceptor cells, pinealocytes, lens fiber and epithelial cells, the cerebellum, and the cerebral cortex. These results indicate that S-Ag is expressed in a wider spectrum of the cell types than previously recognized and that a 1.3-kilobase pair S-Ag promoter segment contains sufficient information to direct appropriate tissue-specific gene expression in transgenic mice.

Tyrosine hydroxylase- and neuropeptide Y-immunoreactive nerve fibers in the pineal complex of untreated rats and rats following removal of the superior cervical ganglia

The distribution of tyrosine hydroxylase (TH)- and neuropeptide Y (NPY)-immunoreactive(IR) nerve fibers in the pineal complex was investigated in untreated rats and rats following bilateral removal of the superior cervical ganglia. In normal animals, a large number of TH- and NPY-IR nerve fibers were present in the pineal capsule, the perivascular spaces, and intraparenchymally between the pinealocytes throughout the superficial pineal and deep pineal gland. A small number of TH-IR and NPY-IR nerve fibers were found in the posterior and habenular commissures, a few fibers penetrating from the commissures into the deep pineal gland. To elucidate the origin of these fibers, the superior cervical ganglion was removed bilaterally in 10 animals, and the pineal complex was examined immunohistochemically. Two weeks after the ganglionectomy, the TH-IR and NPY-IR nerve fibers in the superficial pineal gland had almost completely disappeared. On the other hand, in the deep pineal and the pineal stalk, the TH-IR and NPY-IR fibers were still present after ganglionectomy. These data show that the deep pineal gland and the pineal stalk possess an extrasympathetic innervation by TH-IR and NPY-IR fibers. It is suggested that the extrasympathetic TH-IR and NPY-IR nerve fibers innervating the deep pineal and the pineal stalk originate from the brain.

Melatonin-induced enhancement of antibody-dependent cellular cytotoxicity

Antibody-dependent cellular cytotoxicity (ADCC) is a lytic mechanism in which a specific antibody acts cooperatively with leukocytic effector cells to induce target cell lysis. In this paper, the effect of exogenous melatonin on ADCC was examined. It was found that two evening intravenous injections of melatonin (1 mg/kg b.w.) was sufficient to enhance the capacity of splenocytes to mediate ADCC. This augmented activity returned to normal levels by day 6. Moreover, the opioid antagonist, naloxone, was unable to inhibit the ADCC enhancement, suggesting that melatonin did not operate through a naloxone-sensitive opiatergic mechanism. These results further support the modulatory action of melatonin on immune responses.

An Ig-A-like substance in the chicken's pineal

Immunohistochemistry revealed an Ig-A-like substance on the luminal surface of the pineal follicles and in the parafollicular layer. This substance was observed around 1 week of age and disappeared by 8 weeks at the time when the transformation of the follicular pattern leads to an adult-type pineal tissue.

Differential expression of mRNA and protein encoding retinal and pineal S-antigen during the light/dark cycle

S-Antigen is a soluble cell protein unique to the retina and pineal gland. In the former, it is a well-characterized molecule that participates in light-induced signal transduction in photoreceptor cells. In the latter, the functional role is presently not known. The expression of S-antigen and its mRNA was examined in the rat retina and pineal gland throughout the diurnal cycle and with light interruption of the dark cycle. A cDNA for rat S-antigen was isolated from a pineal gland library to examine the mRNAs. A 1.7-kb mRNA for S-antigen was observed in both the pineal gland and the retina. Retinal S-antigen mRNA was expressed throughout the diurnal cycle and increased with light interruption of the dark cycle. In contrast, pineal gland S-antigen mRNA levels were detectable only during the dark and were absent preceding and during light. The phenotypic expression of immunoreactive S-antigen, identified with two S-antigen monoclonal antibodies (MAbs), MAb A9C6 and MAb C10C10, was analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel (PAGE) and isoelectric focusing (IEF) electrophoresis. Immunoblot analysis of gels after SDS-PAGE revealed a single 46-kDa protein in retina. In contrast, two bands of approximately 43 and 46 kDa were identified in the pineal gland. Immunoblots of the retinal extracts separated by IEF electrophoresis revealed five S-antigen isomers, which vary quantitatively throughout the diurnal cycle and when light interrupted the dark cycle. Immunoblots of the pineal gland samples separated by IEF electrophoresis indicated that the pineal gland possesses four pineal gland-specific forms of S-antigen in addition to the five forms present in the retina. The differences observed in the mRNA and protein analyses suggest tissue-specific structural components for S-antigen in the retina and pineal gland that are not regulated in the same manner.

Serial adoptive transfer of experimental autoimmune uveoretinitis in rats

Experimental autoimmune uveoretinitis (EAU) and pinealitis induced by an interphotoreceptor retinoid-binding protein (IRBP)-derived peptide (R4) was serially transferred into naive recipient rats, using spleen cells from recipients of previous "orders" of transfer. The cells initiating the disease in recipients of the first order were either lymph node cells from rats immunized against peptide R4, or lymphocytes of a cell line specific toward this peptide. The serial transfer was successfully carried out through as many as four orders of sequential recipients.

Experimental autoimmune uveoretinitis and pinealitis induced by interphotoreceptor retinoid-binding protein and S-antigen: induction of intraretinal and subretinal neovascularization

Experimental autoimmune uveoretinitis (EAU) and pinealitis were induced in Lewis rats following hind foot pad injection of interphotoreceptor retinoid-binding protein (IRBP) or S-antigen. A comparison is made in this study of the in vivo and histological changes in uveoretinitis and pinealitis induced by administering similar doses of highly-purified IRBP and S-antigen emulsified in complete Freund's adjuvant (CFA). The time of onset of ocular inflammation after inoculation was slightly later in S-antigen (14-18 days) as compared with IRBP-inoculated animals (10-14 days), while the severity of the inflammation was lower in the latter group. The distribution of inflammation in the anterior segment was similar in both the S-antigen and IRBP sensitized animals but there was major variation in the location of the posterior segment disease. Vasculitis was a predominant feature of IRBP induced disease while chorioretinitis and photoreceptor destruction was more prominent in the S-antigen sensitized animals. A striking feature of this study is that both antigens induced intraretinal and subretinal neovascularization, an observation which has not been reported previously. Inflammation was induced in all pineal glands and as with EAU the severity was closely related to the type of antigen inoculated.

Molecular mimicry between a uveitopathogenic site of S-antigen and viral peptides. Induction of experimental autoimmune uveitis in Lewis rats

S-Antigen (S-Ag) is a well characterized 45,000 m.w. photoreceptor cell protein. When injected into susceptible animal species, including primates, it induces an experimental autoimmune uveitis, a predominantly T cell-mediated autoimmune disease of the retina and uveal tract of the eye, and of the pineal gland. In this study we found an amino acid sequence homology between a uveitopathogenic site of S-Ag, several viral proteins and one additional nonviral protein. An experimental autoimmune uveitis and pinealitis was induced in Lewis rats with these different synthetic peptides, corresponding to the amino sequence of hepatitis B virus DNA polymerase, gag-pol polyprotein of Baboon endogenous virus and gag-pol polyprotein of AKV murine leukemia virus and potato proteinase inhibitor IIa, which contain three or more consecutive amino acids identical to peptide M in S-Ag. Lymph node cells from rats immunized with either peptide M or the different synthetic peptides showed a significant degree of cross-reaction. Mononuclear cells from monkeys (Macaca fascicularis) immunized with peptide M also showed significant proliferation when incubated with either peptide M or synthetic peptides as measured by in vitro lymphocyte mitogenesis assay using [3H]TdR. Based on our findings we conclude that a viral infection may sensitize the mononuclear cells that can cross-react with self proteins by a mechanism termed molecular mimicry. Tissue injury from the resultant autoantigenic event can take place in the absence of the infectious virus that initiated the immune response.

Tumorigenesis and eye abnormalities in transgenic mice expressing MSV-SV40 large T-antigen

Transgenic mice which expressed SV40 large T-antigen under the control of the MSV enhancer and the SV40 promoter were generated. In animals containing an intact MSV enhancer, total lens cataracts and neuroectodermal brain tumors, originating in the pineal organ were observed. In contrast, 5' deletion of the MSV enhancer to a residual 53 bp resulted in a different spectrum of pathologies. Whilst lens cataracts still occurred, no brain tumors could be detected. Instead, fibrosarcomas and adenocarcinomas of the kidneys were induced. In addition, tumors of the endocrine pancreas were observed with both transgene constructs. We conclude that the MSV enhancer element is sufficient to direct the expression of the viral reporter gene to the lens and the pineal organ in transgenic mice. Deletion of the MSV enhancer correlates with the loss of DNA elements responsible for the pineal cell specific expression of SV40 large T-antigen.

Expression of immunoreactivity for Ca-binding protein, spot 35 in the interstitial cell of the rat pineal organ

In the rat pineal organ numerous stellate cells exhibited intense immunoreactivity for calcium-binding spot 35 protein. Because of their peculiar shape and ultrastructure, identical to those of intrapineal S-100-immunoreactive cells, the spot 35-immunoreactive stellate cells were identified as the interstitial cells. The comparison of the morphology and population density of spot 35-, S-100-, and GFAP (glial fibrillar acidic protein)-immunoreactive cells, suggests that spot 35-immunoreactive cells represent a major subpopulation of the interstitial cells, all of which are S-100-immunoreactive and generally considered to be of glial nature, while GFAP-immunoreactive cells represent a minor subpopulation of the interstitial cells located in the proximal part close to the pineal stalk. This is the first report describing the occurrence of the calcium-binding protein in cells of glial nature.

Immune responses to peptides derived from the retinal protein IRBP: immunopathogenic determinants are not necessarily immunodominant

Interphotoreceptor retinoid-binding protein (IRBP), a glycoprotein specific to the retina and pineal gland, induces in immunized rats inflammatory changes in these organs (EAU and EAP, respectively). We report here on the immunological activities in Lewis rats of 10 IRBP-derived peptides. Only one of these peptides (R3) was found to induce high levels of antibodies in immunized rats, as detected by ELISA. On the other hand, the majority of the tested peptides stimulated substantial cellular immune responses, measured by the lymphocyte proliferation assay. None of the tested peptides were recognized, however, by antibodies or lymphocytes from rats immunized with the whole IRBP molecule, thus indicating that these synthetic peptides are nonimmunodominant in the Lewis rat. Two of these peptides, R4 and R9 (which contains R4), were previously found to be immunopathogenic, producing EAU and EAP in immunized Lewis rats. The immune responses to peptide R4 were further examined and the data show that it induces measurable lymphocyte responses only when injected at remarkably high doses (greater than or equal to 67 microgram/rat). Yet, peptide R4 was highly antigenic when tested for stimulation of specifically sensitized lymphocytes in culture. Furthermore, lymphocytes sensitized against R4 exhibited high capacity to adoptively transfer EAU and EAP to naive recipients. The finding of immunopathogenic but nonimmunodominant peptides is discussed.

Alterations of pineal gland and of T lymphocyte subsets in metastatic cancer patients: preliminary results

Melatonin (MLT), the main hormone produced by the pineal gland, has been seen to play a role in antineoplastic activity either by exerting a direct inhibitory effect on cancer cell growth, or by stimulating the immune system. Moreover, MLT blood levels have been shown to be often increased in cancer patients. On the basis of these data, a study was started to evaluate what relation exists between MLT levels and T lymphocyte subsets in patients with metastatic solid neoplasm. The study included 28 patients (breast: 10; non-small cell lung: 18). None of the patients was previously treated for their metastatic disease. Abnormally high MLT levels and a low T helper/suppressor ratio (CD4/CD8) were seen in 10/28 and in 11/28 patients, respectively. Serum mean levels of MLT were significantly higher in patients with low CD4/CD8 ratio than in those with a normal ratio. These results would suggest that immune dysfunctions may represent a signal for MLT release from the pineal in patients with metastatic solid neoplasm.

Rat T-cell lines specific to a nonimmunodominant determinant of a retinal protein (IRBP) produce uveoretinitis and pinealitis

Rat lymphocyte lines were established, with specificity toward two synthetic peptides derived from the interphotoreceptor retinoid-binding protein (IRBP), which specifically localizes in the retina and pineal gland. One of the peptides, R4, is immunopathogenic, producing experimental autoimmune uveoretinitis (EAU) and pinealitis (EAP) in immunized rats, while the other peptide, R3, exhibits no detectable immunopathogenicity in rats. The cell lines carry surface markers specific for the helper/inducer subset of T-lymphocytes. When tested by the proliferation assay, the line cells demonstrated major histocompatibility-restricted vigorous responses against the immunizing (homologous) peptide, but failed to recognize the intact IRBP molecule. This finding is in line with other data indicating that peptides R3 and R4 are nonimmunodominant determinants of IRBP for the Lewis rat. Yet, the cell lines specific for R4 were highly immunopathogenic, producing EAU and EAP in naive rats at numbers as low as 0.25 x 10(6), with histopathological changes similar to those induced by active immunization with this peptide. The immunological capacity of the cell lines was further demonstrated by the finding that spleen cells from recipient rats of these lines responded well against the homologous peptides. The uniqueness of this system, in which lymphocytes specific toward a nondominant determinant are immunopathogenic, is underscored and the possible mechanisms of disease induction are discussed.

Rat pineal S-antigen: sequence analysis reveals presence of alpha-transducin homologous sequence

S-antigen (S-Ag) is a soluble, highly antigenic protein, the administration of which induces autoimmune uveitis. This protein is found in the retina and pineal. Retinal S-Ag from three species has been sequenced. In this study rat pineal S-Ag was sequenced. Clones were isolated from a rat pineal lambda gt11 cDNA library by probing with a 300 bp fragment of mouse retinal S-Ag cDNA containing the 5'-coding region. The largest clone isolated (RPS-118; 1364 bp) contained the entire coding sequence. Comparison of the rat pineal and mouse retinal S-Ag nucleotide sequences indicated a high homology (95%). The deduced amino acid sequence was found to contain 403 residues (congruent to 44 992 Da). Comparison of the rat pineal and mouse retinal S-Ag amino acid sequences also revealed high homology (97%). The similarity of both the nucleotide and amino acid sequences of rat pineal and mouse retinal S-Ag indicates that expression of the S-Ag gene in both tissues is similar. Further analysis of the rat pineal S-Ag sequence indicated that it contained essentially the same major uveitopathogenic region of S-Ag present in bovine retina; minor uveitopathogenic sites were somewhat different. As is true of retinal S-Ag, rat pineal S-Ag contains the same consensus phosphoryl-binding site present in many GTP/GDP-binding proteins and a homologous sequence found in the C-terminus of alpha-transducin. These sequences may play a role in the action of pineal S-Ag in transmembrane signal transduction.

Uveitopathogenic sites in bovine S-antigen

Experimental autoimmune uveitis (EAU) was observed in Hartley guinea pigs following immunization with high doses (200 micrograms) of four synthetic peptides designated peptide 3, K, N and M which correspond to amino acid positions 221-240, 241-260, 281-302, and 303 to 320 respectively in bovine S-antigen. Histopathologically, a moderate inflammatory response involving the uveal tract and retina was observed using peptide N and peptide M as immunogens, whereas peptide 3 and peptide K caused only a mild inflammatory response with very few inflammatory cells in the retina. In contrast, animals with EAU showed an associated pinealitis (EAP) characterized by an extensive lymphocytic infiltration of the central and subcapsular areas of the pineal gland. Lymph node cells of guinea pigs immunized with peptide 3, peptide K, peptide N or peptide M showed strong in vitro proliferative responses against the respective immunizing peptide as measured by [3H] thymidine uptake. The results suggest that under appropriate experimental conditions S-antigen may contain multiple pathogenic sites. The relevance of these studies in the pathogenesis of EAU is discussed.

Enkephalin-like immunoreactivity in neurons in the human pineal gland

Adult human pineal glands were prepared for immunohistochemical analysis using antisera against Leu-enkephalin, neuropeptide Y, dopamine-beta-hydroxylase and vasoactive intestinal polypeptide. The material shows small neurons located in septae and along the capsule of the gland which exhibit enkephalin-like immunoreactivity. The neurons have fairly extensive dendritic arbors and immunoreactive axons are present in the septae and beneath the capsule, particularly in a perivascular location, and occasionally extend into lobules of the gland among parenchymal cells. No consistent immunoreactivity was observed with other antisera but bundles of axons exhibiting dopamine-beta-hydroxylase or neuropeptide Y-like immunoreactivity are observed in some of the material in a perivascular location.

Effects of continuous light exposure on the rat retina and pineal gland

We examined the effects of intense continuous light (400 ftc for 10 days) on the morphology and immunoreactivity of the rat retina and pineal gland. The light treatment caused severe degeneration in the retina, with loss of most photoreceptor cells, and produced a marked decrease in S-antigen immunoreactivity in this organ. Unlike the retina, the light treatment had minimal effects on the histological structure of the pineal gland. However, pineal glands of light-treated rats exhibited a substantial reduction in their S-antigen immunoactivity, as demonstrated immunohistochemically and quantitatively verified by the rocket immunoelectrophoresis technique: pineal glands of light exposed rats had approximately two-thirds of the S-antigen immunoactivity of the untreated controls. Light treatment was also found to reduce both uveoretinitis and pinealitis in rats immunized with S-antigen. Yet pinealitis was not affected by light exposure in rats, as they were enucleated before treatment. This study thus provides new information to support the notion that the mammalian pineal gland is directly associated with light detection by the retina.

Differential effects of cyclosporins A and G on functional activation of a T-helper-lymphocyte line mediating experimental autoimmune uveoretinitis

The effect and relative efficiency of cyclosporin A (CsA) and cyclosporin G (CsG) on suppressing the activation of primed autoimmune rat T-helper lymphocytes were assayed. The autoimmune T-helper cells (ThS) are a long-term line specific to the retinal soluble antigen (SAg) and can adoptively transfer experimental autoimmune uveoretinitis (EAU), after in vitro reactivation with antigen or mitogen, to naive syngeneic hosts. Antigen-driven production of interleukin-2 (IL-2) and antigen-driven proliferation were inhibited in a dose-dependent manner and to a similar extent at each of the respective cyclosporin concentrations. CsA was 8-10 times more potent than CsG, with ID50-CsA occurring at 0.5 to 2 ng/ml, and ID50-CsG at 5 to 20 ng/ml, depending on the experiment and the cyclosporin batch. Addition of exogenous lymphokines in the form of rat spleen concanavalin A (Con A)-conditioned medium (SCM) or recombinant IL-2 (but not recombinant IL-1) was able to reverse only about half of the inhibition, as measured along the linear part of the dose-response curve. Inhibition of IL-2 production was lost if a maximally inhibitory dose of cyclosporin was added to the cultures later than 8 hr after antigen stimulation, while proliferation was still suppressed to 50% by cyclosporin added as late as 12 hr and could not be restored by addition of SCM. Both cyclosporins at concentrations that blocked proliferation and IL-2 production significantly suppressed the generation of high-affinity and low-affinity IL-2 receptors by ThS in response to antigen (as assayed by direct binding of 125I-IL-2). These results suggest that CsA and CsG inhibit antigen-induced expansion of ThS by interfering with more than one activation step. In contrast, the in vitro activation of the uveitogenic potential of ThS cells, incubated with antigen in the presence of CsA or CsG and adoptively transferred into untreated recipients, was not affected by the cyclosporins. Thus, triggering of the pathogenic potential of primed autoimmune T-helper lymphocytes can take place in the presence of cyclosporin and in the absence of cellular proliferation.

Comparison of calbindin D-28K immunoreactivity in superficial pineal bodies of mongolian gerbil and rat

Immunocytochemical reaction for demonstration of calbindin D-28K has been performed in superficial pineal bodies of the Mongolian gerbil (Meriones unguiculatus) and the rat. Whereas in the Mongolian gerbil there were no clearly expressed calbindin immunoreactive cells, these were numerous in the rat pineal body. Here the calbindin-positive cells - probably pinealocytes - were disposed along capillaries. In view of the role of calbindin in binding and transporting calcium and regulating its intracellular levels, the absence of this protein in the gerbil pineal body has been interpreted as signifying the inability of pinealocytes to eliminate intracellular calcium with possible consequent formation of acervuli.

Ultrastructural identification of calbindin-D28k-immunoreactive cells in the rat superficial pineal body

The vitamin-D-dependent calcium-binding protein, calbindin-D28k, was detected immunocytochemically in the majority of pericapillary pinealocytes of the rat superficial pineal body. The interstitial cells were calbindin-negative. The significance of these findings is discussed.

Distribution in the macaque pineal of nerve fibers containing immunoreactive substance P, vasopressin, oxytocin, and neurophysins

The distribution of nerve fibers containing immunoreactive substance P (SP), estrogen-stimulated neurophysin (ESN), nicotine-stimulated neurophysin (NSN), oxytocin (OT), and vasopressin (VP) was examined in the epithalamic area of adult male and female macaques. Perfused or immersion-fixed epithalamic tissues, sectioned, and mounted on glass slides were processed through the avidin-biotin immunofluorescence method. Fibers containing immunoreactive SP were observed in the pineal organ along the periphery, in the perivascular space, and dispersed between the pinealocytes. Fibers were often observed in the pineal stalk region, and the habenular nuclei had high concentration of immunoreactive SP. Immunoreactive ESN fibers were observed in the stria medullaris, in the lateral habenula, in the pineal stalk, and in the pineal organ. Within the pineal, fibers containing ESN were present in the perivascular space, often concentrated in the walls of blood vessels, but also dispersed between pineal cells. Fibers containing OT, NSN, and VP were also present in the macaque pineal, but in lower quantities compared with fibers containing ESN. These studies show that the pineal of subhuman primates contain nerve fibers (ESN, NSN, VP, OT) of possibly hypothalamic origin. It also has a rich supply of SP fibers, which might be of habenula origin, peripheral parasympathetic ganglia origin, or both. The functional significance of these peptidergic nerve fibers remains to be determined. However, there are indications that they might be involved in regulation of blood flow and release of secretory products from the pinealocytes.

Uveitogenic potential of lymphocytes sensitized to interphotoreceptor retinoid-binding protein

In our previous study rats immunized with bovine retinal interphotoreceptor retinoid-binding protein (IRBP) were found to develop inflammation in the eye and the pineal gland. This inflammatory disease was distinct in several aspects from experimental autoimmune uveoretinitis (EAU) induced by the retinal S-antigen (S-Ag). The current study examined the adoptive transfer of IRBP-induced EAU. We established that lymphocytes from IRBP immunized donor rats were capable of transferring EAU after in vitro stimulation with either IRBP (lymph node or spleen cells) or concanavalin A (spleen cells only). Recipients of these cells developed uveoretinitis and pinealitis identical to the actively induced disease. As compared with the S-Ag system, recipients of IRBP sensitized cells developed disease earlier, and smaller numbers of cells were needed to transfer EAU. Development of inflammation was directly related to a cellular response to the specific retinal antigen used for sensitization. Moreover, the unique nature of ocular inflammation was reestablished in the IRBP system: high proportions of polymorphonuclear leukocytes were found in the inflamed tissue of certain recipients despite a lack of a humoral response to the specific antigen. In contrast to the eye, only mononuclear leukocytes comprised the inflammation in the pineal gland.

Identification of a uveitogenic cyanogen bromide peptide of bovine retinal S-antigen and preparation of a uveitogenic, peptide-specific T cell line

Peptide fragments of bovine retinal S-antigen produced by cyanogen bromide (CB) digestion have been purified and tested for their ability to induce experimental autoimmune uveoretinitis (EAU) and pinealitis (EAP) in Lewis rats. Following immunization with the various peptides in complete Freund's adjuvant, one of the peptides, CB123, was found to be potently uveitogenic. A CB123-specific, class II restricted T helper lymphocyte line (R208) prepared from one of the CB123 peptide-immunized animals by repeated in vitro selection with purified CB123 was able to transfer severe EAU and EAP to naive rats. Peptides CB36, CB46, CB51 and CB66 were immunogenic as assessed by the presence of antibodies detected in the enzyme-linked immunosorbent assay and sensitized lymphocytes found in [3H]thymidine incorporation assays using lymphocytes from the peptide-immunized rats, but they did not induce significant EAU or EAP. Antibodies induced by immunization with the peptides also bound intact S-antigen, unlike the lymphocytes which were only weakly responsive to S-antigen. Cross-reactivity of antibodies and lymphocytes from CB51 and CB66 immune animals suggested that these peptides overlap and contain a common epitope. No measurable immunity to any CB peptide or intact S-antigen was found in the animals immunized with peptide CB26. Although a T cell line (R17) raised to human S-antigen was also able to transfer EAU, it was weakly responsive to the CB123 peptide; also, the R208 line did not respond well to human S-antigen. Since both human and bovine S-antigen are uveitogenic, these results suggest that the uveitogenic epitope in CB123, which is of bovine origin, is not the same as the uveitogenic epitope of the human antigen.

Pineal-retinal molecular relationships: distribution of "S-antigen" in the pineal complex

The immunocytochemical localization of S-antigen, a specific protein first discovered in retinal photoreceptors, was studied in the pineal complex of vertebrates (eel, pike, frog, lizard, passerines, mouse, hamster) using monoclonal antibody immunofluorescence. S-antigen immunoreactivity was demonstrated concurrently in retinal photoreceptors and in most pineal phototransducers of all species, i.e. in pineal cells of the receptor series (cone-like, modified photoreceptor cells, pinealocytes) and in cone-like photoreceptors of the frog frontal organ and lizard parietal eye. The labelling was distributed either in all compartments of these cells, or restricted to outer segments. The functional significance of the S-antigen as well as some phylogenetic and ontogenic implication of this marker are discussed.

Concanavalin A-binding glycoproteins in the subcommissural and the pineal organ of the sheep (Ovis aries). A fluorescence-microscopic and electrophoretic study

Glycoproteins rich in mannosyl or glucosyl residues were analyzed in the subcommissural organ (SCO) and the pineal organ of the sheep (Ovis aries). By use of concanavalin A labelled with fluorescein isothiocyanate, fluorescent material was found both in ependymal and hypendymal cells of the SCO. In the pineal organ, either isolated or grouped parenchymal cells showed a marked fluorescence. These cells may correspond to ependymal elements also called "interstitial cells" or "supporting cells". In addition, scarce slender, fluorescent processes were observed in the pineal parenchyma. The techniques of electrophoresis and electrotransfer on nitrocellulose paper have been applied to analyze the glycopeptide content of the SCO and the pineal organ in comparison to cerebellar and cerebral fractions solubilized by use of Triton X 100. Approximately 30 different concanavalin A-reactive glycopeptides were revealed in each fraction. In the SCO extract four glycopeptides (30, 54, 72, 100 kd) might correspond to subunits of the glycoprotein(s) characteristically stored in the ependymal cells of the SCO. In addition, two glycopeptides (32/33, 115 kd) are specific to the pineal organ extract. The possible similarity of the concanavalin A-reactive material in both organs is discussed and a putative secretory activity of the pineal ependymal cells is postulated.

Demonstration of differential immunohistochemical localization of the neuron-specific enolase antigen in rat pinealocytes

A refined method for the immunohistological demonstration of neuron-specific enolase (NSE) on 1- to 2-micron Epon-812 section gave characteristic staining of cerebral and cerebellar neurons. This method has made it possible to obtain a more detailed characterization of the heterogeneity of rat pinealocytes in the superficial portion of the rat pineal complex. Thirty adult male rats have been studied, five of which were used in a photometric analysis of the distribution of NSE. Pinealocytes stained either intensely or weakly for the NSE antigen and exhibited an uneven distribution within a given region. Further analysis of the gland revealed a distal to proximal decrease in stain intensity. It is suggested that the more strongly stained cells, being concentrated distally, are under sympathetic control.

Uveoretinitis and pinealitis induced by immunization with interphotoreceptor retinoid-binding protein

Rats immunized with microgram amounts of interphotoreceptor retinoid-binding protein (IRBP), a glycoprotein which localizes specifically in the eye and pineal gland, developed uveoretinitis and pinealitis. The severity and onset of changes were found to be dose-related and to be enhanced by B. pertussis bacteria. In general, the inflammatory changes induced by IRBP resembled those provoked by S-antigen (S-Ag), but significant differences were noted between the two diseases. The possible usefulness of the new experimental autoimmune disease is discussed.

Rabbit ocular and pineal autoimmune response to retina antigens

Different forms of experimental autoimmune uveitis (EAU) can be produced by varying protocols to present different autoantigens to several species of experimental animal. We have studied the clinical, histological and serological responses of rabbits to footpad injection of various fractions of retina extract. Rabbits injected with retina extract or S antigen developed posterior uveitis. However, rabbits injected with retina extract, also developed an anterior uveitis and pinealitis not seen in rabbits receiving S antigen. The Serological response of rabbits to retina extract was different than that to purified S antigen. Antisera of rabbits receiving retina extract reacted with rabbit retina and pineal gland as well as with guinea pig retina but not with guinea pig pineal gland. In contrast anti-S antigen sera reacted with rabbit retina and guinea pig retina and pineal gland but not with rabbit pineal gland. Gel filtration chromatography of the ammonium sulfate supernate of retina extract was used to differentiate the antigens with which these two sera reacted. An analysis of these experiments gives preliminary evidence of an autoantigen(s) of rabbit retina and pineal gland that is not S antigen. The existence of multiple autoantigens common to retina and pineal gland in various species is significant in that it further underscores the relationship of these tissues. Furthermore, it is not unrealistic to expect more than one autoantigen of retina or uvea to be involved in autoimmune uveitis.

Neuropeptide Y (NPY)-like immunoreactivity in the guinea pig pineal organ

Relatively little is known about mammalian pineal neuropeptides. In the present study neuropeptide Y-like immunoreactivity (NPY-LI) was examined in the guinea pig pineal gland. NPY-LI was restricted to few intrapineal nerve fibers of faint fluorescence intensity. They showed no preferential localization with regard to the different pineal portions. As catecholaminergic fibers are abundant in the guinea pig pineal gland, the scarcity of NPY-LI fibers indicates that in the pineal colocalization of noradrenaline and NPY-LI is not a regular feature, in contrast to other organs. The possibility exists that in the pineal NPY-LI fibers are not of peripheral sympathetic but of central origin.

S-antigen immunoreactivity in human pineal glands and pineal parenchymal tumors. A monoclonal antibody study

Using a four-step immunoperoxidase (PAP) method and the monoclonal antibody MAbA9-C6 (MAbA9-C6), which defines an epitope of the retinal S-antigen (S-Ag), we investigated the S-Ag immunoreactivity in human fetal, newborn, infantile and adult pineal glands and in 13 human pineal parenchymal tumors. S-Ag immunoreactivity was demonstrated in a few cells in one of the four fetal and in both infantile glands. Eight of nine adult pineal glands contained isolated MAbA9-C6-positive cells. In two of seven pineocytomas showing neuronal or gangliogliomatous differentiation a few scattered cells displayed S-Ag positivity; two of four pineoblastomas contained small groups of strongly immunoreactive neoplastic cells; two malignant pineocytomas did not demonstrate any S-Ag immunoreactivity. Our results indicate that isolated cells in human pineal gland retain some of the cytochemical characteristics of photoreceptor cells recognized by the MAbA9-C6, and that S-Ag immunoreactivity may be occasionally expressed in pineal parenchymal tumors.