S-antigen in the developing retina and pineal gland: a monoclonal antibody study

Spleen cells of BALB/c mice, previously immunized with bovine retinal S-antigen, were fused with Sp2/0-Ag14 mouse myeloma cells. Two monoclonal antibodies (MAbs) MAbA9-C6 (IgG2a isotype) and MAbA1-G5 (IgG1 isotype) were selected on the basis of reactivity in an ELISA and immunofluorescent assay. In radioimmunoassay MAbA9-C6 and MAbA1-G5 do not compete and appear to define unrelated epitopes of S-antigen. Both MAbs reacted in the ELISA assay, whereas only MAbA9-C6 bound to S-antigen in fixed tissue sections. Because MAbA9-C6 was useful for immunocytochemistry, it was studied in more detail. MAbA9-C6 bound to all vertebrate retinas tested including human, bovine, guinea pig, and mice. The immunoreactivity of MAbA9-C6 also was studied in the developing rat retina and pineal gland. In the morphologically undifferentiated retina, assessed by conventional light microscopy, there was an incomplete separation of the outer neuroblastic cells. However, in the same retina a distinct zone, corresponding to S-antigen immunoreactivity, was present indicating antigenic differentiation with regard to S-antigen at this stage of retinal development. In the pineal gland, S-antigen immunoreactivity was first observed in the three day old rat and at all stages examined thereafter. The usefulness of these two MAbs in the study of the embryologic development of the retina and of the antigenic epitopes of S-antigen is discussed.

Immunocytochemical demonstration of retinal S-antigen in the pineal organ of four mammalian species

By means of immunocytochemistry retinal S-antigen is selectively demonstrated in retinal photoreceptor cells of the rat and in pinealocytes of the hedgehog, rat, gerbil and cat. Brain areas surrounding the pineal organ are immunonegative. The immunoreactive material is evenly distributed in the perikarya of the cells. Occasionally, inner segments of retinal photoreceptors and processes of pinealocytes are also stained. The outer segments of retinal photoreceptors display a strong immunoreaction. In both pinealocytes and retinal photoreceptors the intensity of the immunoreaction varied considerably among individual cells. The immunocytochemical demonstration of retinal S-antigen in mammalian pinealocytes indicates that these cells still bear characteristics of photoreceptors. This finding is in accord with the concept that mammalian pinealocytes are derived from pineal photoreceptor cells of poikilothermic vertebrates.

The mononuclear phagocyte system of the mouse defined by immunohistochemical localization of antigen F4/80: macrophages of endocrine organs

Macrophages of endocrine organs have been identified by immunohistochemical localization of the macrophage-specific antigen F4/80. F4/80+ cells line vascular sinuses and capillaries in anterior and posterior pituitary, adrenal cortex, corpus luteum, parathyroid, pineal gland, and islets of Langerhans. In testis approximately 20% of interstitial cells are F4/80+. F4/80+ cells infiltrate corpus luteum in increased numbers during luteolysis.

Lymphopineal tissue in the chicken

We have studied the chicken's pineal gland by light and electron microscopy at 3 and 4 weeks of age. The results indicated that lymphocytes, plasma cells, secretory cells, basophil and eosinophil granulocytes enter the parenchyma and a new histologically defined tissue is formed which we call lymphopineal tissue. Inside the pineal parenchyma, the number of thymidine labeled cells is almost three times higher than in the interstitium suggesting that the pineal's products might be blastogenic for the cells and/or exert an influence on post-thymic T-cell differentiation.

Functional lymphocytes in the chicken pineal gland

The primary antibody response of lymphoid tissue occupying the pineal gland of 6-wk-old chickens was studied subsequent to injection of the carotid artery with sheep red blood cells (SRBC) or bovine serum albumin (BSA). Injection of SRBC did not produce plaque-forming cells (PFC) among pineal lymphocytes whereas BSA stimulated synthesis of anti-BSA immunoglobulin in pineal lymphoid tissue. A cytotoxic assay using appropriate anti-lymphocyte sera indicated that single-cell suspensions of pineal lymphocytes were composed of 42% B lymphocytes and 51% T lymphocytes. Bursal and thymic lymphocytes labeled with tritiated thymidine migrated into pineal lymphoid tissue when injected into 4- and 5-wk-old naive chicks. These observations indicate that the bursa and thymus make equivalent contributions to the lymphoid mass in the chicken pineal gland. Challenge of pineal-established lymphocytes by antigen introduced via the blood vascular system suggests that soluble antigens--rather than particulate ones--stimulate antibody production in the pineal gland. Collectively, these studies indicate that the pineal gland should be considered as a functional component of the chicken's lymphomyeloid system.

Regional, cellular, and subcellular distribution of Thy-1 antigen in rat nervous tissues

The regional, cellular, and subcellular distribution of Thy-1 antigen in rat nervous tissues was investigated with rabbit and anti-rat thymus antiserum. Thy-1 antigen was found most abundantly in the cerebrum, including the cerebral cortical layer, caudate nucleus, thalamus, and hypothalamus, and in the midbrain. It was found in lower amounts in the pons, medulla oblongata, cerebellum, and spinal cord. The content of Thy-1 antigen, however, was low in the retina, cervical sympathetic ganglion, and sciatic nerve, and there was little in the pineal body and adrenal medulla. Thy-1 antigen was present in the neuronal cell-enriched fraction, whereas the glial cell-enriched fraction lacked Thy-1 antigen. In a subcellular fractionation study, Thy-1 antigen was found to occur mainly in the synaptosomal membrane and microsomes and was low in the highly purified myelin fraction. The amount of Thy-1 antigen in the cerebral synaptosomal fraction was much higher than those in the cerebellar synaptosomal fraction. The distribution of Thy-1 antigen among the respective areas within the cerebrum was not significantly different, and it is suggested that Thy-1 antigen may be present evenly in the neuronal membranes of the cerebrum. Based on these results, Thy-1 antigen is considered to represent a useful marker of cerebral neuronal membranes, especially in the synaptic region, regardless of the kind of neurotransmitters.

[Factor from rat and bovine pineal organs immunologically and biologically related to luliberin]

Luteinizing hormone releasing hormone (LH-RH, luliberin) was revealed in the pineal organs of rats and cattle. The luliberin content per organ varied in rats from 5 to 66 ng, depending on sex and age. In some cases it could not be revealed by the direct radioimmunological method in the organ extracts, while neurohormone was detected by chromatography on carboxymethylcellulose or on Sephadex G-15. About 0.5 ng of LH-RH is contained in the bocine pineal organs, and the neurohormone competed with 125I-LH-RH for binding with a specific antiserum in the same way as synthetic luliberin. Mobility of LH-RH from the bovine and rat pineal organs during carboxymethylcellulose chromatography in the column coincided with such for synthetic LH-RH and the neurohormone from the rat hypothalamus. Besides, luliberin from the bovine pineal glands injected intraperitoneally to rats led to elevation of the LH blood level. No such effect occurred when luliberin from the epiphyses was preliminarily incubated with the LH-RH antiserum. A possible role played by luliberin in the pineal organ is discussed.

Pineal gland involvement in retina-induced experimental allergic uveitis

A form of experimental allergic uveitis (EAU) can be elicited in guinea pigs by injection of an extract of homologous retina homogenate (S preparation). These guinea pigs exhibit clinical and histological ocular disease as well as cellular and humoral immune responses to S preparation. Recent studies have shown an immunofluorescent crossreactivity of the sera of these animals (anti-S) with retinal photoreceptors and pinealocytes. The experiments presented in this paper demonstrate pineal gland involvement during the course of S preparation-induced EAU. There is lymphocytic infiltration of the pineal gland, with corresponding loss of antigen reactivity and some disturbance in cell structure. Pineal gland infiltrate can be seen before observable retinal involvement. Similarity of the reactive substances in retinal photoreceptors and pinealocytes is demonstrated by a reaction of identity in immunodiffusion studies and similar mobilities in immunoelectrophoretic studies of S preparation and pineal gland extract with anti-S serum. The relationship of the retinal and pineal substances to each other, as well as their role in disease development in the animal model and possibly in human uveitides, are discussed.

Pineal reactivity of anti-retina sera

Specific immunofluorescence has been demonstrated in the guinea pig pineal gland by homologous sera from guinea pigs injected with an extract of retina homogenate. This fluorescence appears to be in the cytoplasm and is evenly distributed among the cells of the pineal gland. Specific immunofluorescence in the retina has been previously demonstrated by these sera.

Immunocompetence of pinealectomized and simultaneously pinealectomized and thymectomized rats

The cellular and antibody-mediated immune responsiveness was studied in adult rats which had the pineal and/or the thymus gland removed within 36 hours after birth. The immunolgical parameters measured were: Skin graft rejection, haemolytic plaque formation, and haemagglutinating antibody formation in response to sheep red blood cells and the stimulation of lymphoid cells from the spleen by phytohaemagglutinin in lipopolysaccharide. The removal of the pineal gland had little effect on the degree of immunocompetence in normal or immunosuppressed animals. In some of the immunological tests an accelerated response was observed, which suggests that lymphoid cells from pinealectomized or pinealectomized-thymectomized animals proliferate more rapidly upon contact with antigen or mitogen. This accelerated cell proliferation, unlike the immunodepression of the host, could explain the enhanced growth of transplantable tumors observed in pinealectomized animals.