Blood mononuclear cells from patients with psoriasis exhibit an enhanced adherence to cultured vascular endothelium.

Blood mononuclear cells (MNC) from patients with psoriasis were more adherent to monolayers of endothelial cells prepared from human umbilical cord vein than otherwise similar cells from control subjects. This increase in adherence occurred in the presence (mean 37% increase; p less than 0.01) and absence (mean 47% increase; p less than 0.05) of 10% autologous serum and was not related to the disease severity of the patients. The augmented adhesiveness of the patients' cells was also apparent when using monolayers of endothelial cells isolated from human skin. The levels of immune complexes, complement, alpha 2-macroglobulin, acute phase proteins (alpha 1-acid glycoprotein, C-reactive protein and alpha 1-antitrypsin), and tumor necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha), and interleukin-1 beta (IL-1 beta) in the patients' sera were within normal limits. When MNC were added to endothelial monolayers that had been incubated with either TNF alpha or the highest concentration of rIL-1 beta used in the study, both the patients' and control's cells exhibited a similar increase in attachment (p less than 0.01). Pretreatment of endothelium with interferon-gamma did not enhance the attachment of MNC from either group of subjects. The augmented adherence of the patient's MNC appears to be due to an abnormal adhesiveness of the lymphocytes rather than the monocytes and is not related to an enhanced expression of the cell-surface adhesion molecules CD11a/CD18. It is likely that the circulating MNC of psoriatic patients may be predisposed for extravasation into skin.

Selective binding of peripheral blood lymphocytes to the walls of cerebral vessels in frozen sections of human brain.

In order to identify the factors that control the binding of blood leucocytes to cerebral blood vessels we have modified and applied the frozen section assay of Stamper and Woodruff to the study of human brain. Cryostat sections of brain tissue obtained at post mortem were overlaid with blood lymphocytes and experimental conditions were defined which permitted optimum binding of the cells to transected blood vessel walls. The maximal binding of lymphocytes to cerebral vessels occurred when 6 x 10(6) lymphocytes were overlaid onto brain sections for 30 min at 7 degrees C with gentle agitation. Only a small proportion (0.01%) of the added lymphocytes bound to exposed cerebral vessels. However, lymphocytes were far more adherent than monocytes and polymorphonuclear cells (7-fold and 11-fold respectively: p < 0.001) and activation of lymphocytes with IL-2 enhanced their binding to blood vessel walls (mean 130% increase; p < 0.03). Further analysis revealed that CD4-positive T lymphocytes were the predominant cell population binding to the blood vessels. Antibody blocking studies showed that lymphocyte binding to cerebral blood vessels was inhibited by pretreating the lymphocytes with anti-CD11a, anti-CD18 or anti-CD49d (p < or = 0.02) and immunohistochemical studies revealed the presence of the counter-receptors ICAM-1 (CD54) and VCAM-1 (CD106) for these adhesion molecules in addition to the presence of E-selectin (CD62E) and P-selectin (CD62P) on the cerebral blood vessels. The establishment of a technique in situ which measures selective binding of CD4-positive peripheral lymphocytes to sections of cerebral blood vessels will assist in the molecular characterization of factors that control the interaction of leucocytes with the blood-brain barrier in health and disease.

Transendothelial chemotaxis in vitro of human monocytes.

Porcine aortic vascular endothelial cells were grown to confluence on microporous PTFE membranes and incorporated into a two-compartment chemotaxis assembly. Human peripheral blood mononuclear cells (20-25% monocytes) were placed in the upper compartment and zymosan-activated human serum (ZAHS) as chemoattractant in the lower compartment. Over a 3 h period monocytes migrated across the endothelialized membrane and adhered to a collecting filter sited in the lower compartment. Addition of ZAHS to the cell suspension in the upper compartment virtually abolished the migration response whilst only minimal leucocyte migration was supported by the bare unendothelialized PTFE membrane. The extent of transendothelial monocyte chemotaxis was dependent upon the concentration of chemoattractant in the lower compartment and upon the cell density of the suspension containing monocytes. A confluency test of fluid flow across the endothelialized filter showed that monocyte migration could take place without disturbing endothelial barrier function. The culture system is easy to assemble and the method provides experimental versatility.

The use of human lymphoid cell line lymphokine preparations (LCL-LK) as working standards in the bioassay of human leucocyte migration inhibition factor (LIF).

The leucocyte migration inhibition test in agarose as described by Clausen (1971) was modified into a statistically designed assay of LIF activity using human polymorphonuclear leucocytes from single blood donors. Individual assays included a laboratory standard of lymphokine with LIF activity prepared from the culture supernatants of the RPMI 1788 human lymphoblastoid cell line (LCL-LK). Analysis of 157 LIF assays revealed simple criteria by which the acceptability of an individual assay could be judged before subjecting it to statistical analysis. The failure of LIF assays to meet these criteria of acceptability was particularly associated with low areas of control polymorph migration in the absence of lymphokine ('spontaneous migration'). We demonstrate that the statistically designed assay permits the measurement, with precision, of LIF activity in units/ml by reference to a working standard of LCL-LK. We illustrate the use of this assay in the measurement of LIF activity generated by tuberculin-stimulated human peripheral blood lymphocytes.

A reappraisal of the macrophage electrophoretic mobility (MEM) test for the measurement of lymphokine activity.

Using a cell electrophoretic apparatus, which was sensitive in detecting small changes in electrophoretic mobility (EPM), the macrophage electrophoretic mobility (MEM) test was investigated as a routine method for detecting lymphokine activity. Electrophoretic analysis of guinea-pig macrophages revealed 2 main subpopulations, one with an EPM of 0.90 micron cm s-1 V-1 (fast) and the other, an EPM of 0.83 micron cm s-1 V-1 (slow). From 23 experiments the fast and slow populations were found to consist of 90% and 10% cells, respectively. When macrophages were incubated with standard guinea-pig lymphokine preparations there was a significant decrease in the fast population with a corresponding increase in the slow population. This lymphokine induced 'slowing' of the macrophages was shown to be very reproducible. Since only 50% of macrophages of high EPM were observed to respond to lymphokine activity, it is not surprising that the MEM test has failed in the past when investigators have accepted as significant a 10-15% reduction in EPM, estimated from measurements made on only 10 macrophages. Parallel bioassays indicated that there were appreciable potency differences for macrophage slowing factor (MSF) and macrophage migration inhibition factor (MIF) activities in the lymphokine preparations used which suggest that these activities may be due to different molecular entities.

An improved method for the purification of retinal S-antigen using selective hydrophobic adsorption chromatography.

This paper describes the use of phenyl-Sepharose CL-4B as a solid-phase hydrophobic adsorbent in the purification of S-antigen from protein extracts of bovine, porcine and human retina. Chromatographic conditions were ascertained whereby the majority of contaminating proteins were bound to the adsorbent leaving S-antigen in the liquid phase. In combination with size fractionation on Ultrogel AcA, the method conveniently yielded porcine and bovine S-antigen preparations up to 100% purity. Immunogenicity of purified S-antigens was verified by induction of experimental autoimmune uveoretinitis in albino Lewis rats. The method is preparative in scale, fast in performance and yields S-antigen in high purity and antigenic potency.

Passive administration of antibody against retinal S-antigen induces electroretinographic supernormality.

Electroretinographic supernormality, affecting both the a- and b-waves of the electroretinogram (ERG), occurs consistently before the onset of experimental autoimmune uveoretinitis (EAU) in rabbits and rats. To investigate the possible role of antibody to S-antigen (S-ab) in this phenomenon, affinity-purified polyclonal rat S-ab was injected intravenously into normal rats and administered to isolated rat eyecup preparations by bolus perfusion. In both situations, ERG supernormality was observed. The effect in vivo peaked 90 min after injection, and ERG changes in vitro were observed within 15 sec. The ERG response in vivo and in vitro was dose dependent and was abolished in vivo by pretreatment with cyproheptadine (a serotonin antagonist). The ERG was not affected in either system by a control rat antibody (antiovalbumin) or by murine monoclonal or rabbit polyclonal antibodies to S-antigen. The induction of ERG supernormality in vivo and in vitro by homologous S-ab indicates the operation of species-specific mechanisms both involving and bypassing the blood-retinal barrier and highlights a significant role for humoral autoimmunity in the pathogenesis of S-antigen-induced EAU in the rat.

A new method for studying the selective adherence of blood lymphocytes to the microvasculature of human retina.

PURPOSE: To develop a sensitive and reproducible technique for measuring the adherence of blood lymphocytes to vessel walls exposed in sections of human retina and for examining the role of lymphocyte and vascular adhesion molecules in these events. METHODS: Cryostat sections of human retina were overlaid with blood lymphocytes from healthy subjects, and experimental conditions were sought by which preferential attachment of the cells occurred to blood vessel walls in the retinal sections. Adherent lymphocytes were identified by staining with methyl green-thionine, and transected blood vessels were identified by their structure and by staining of basement membranes with periodic acid-Schiff. The adherence of enriched preparations of CD4+ (T-helper) and CD8+ (T-cytotoxic) lymphocytes, of interleukin-2 (IL-2)-activated cells, and of lymphocytes from patients with ocular Behçet's disease was examined. The distribution of adhesion molecules on retinal vessel walls was determined by immunohistochemistry, and the contribution of leukocyte integrins to lymphocyte binding was studied by blocking experiments with monoclonal antibodies. RESULTS: The optimal selectivity of blood lymphocyte attachment to retinal vessel walls occurred when purified lymphocytes were suspended in culture medium with 10% fetal calf serum and overlaid onto retinal sections for 30 minutes at 23 degrees C with gentle agitation. Under these conditions, 92% of the lymphocytes that adhered to the section were confined to the retinal microvasculature, and CD4+ T cells were more adherent than CD8+ T cells (P < 0.01). Prior exposure of normal lymphocytes to IL-2 enhanced their binding to retinal blood vessels, and lymphocytes from patients with Behçet's disease showed supranormal vascular adherence (P < 0.005). Many transected vessels stained positively for CD31; PECAM (mean 62%), CD54; ICAM-1 (mean 73%), CD62E; E-selectin (mean 35%), CD62P; P-selectin (mean 61%), and CD106; VCAM-1 (mean 42%). However, these vascular adhesion molecules occupied < 20% of the area of the blood vessel walls. Lymphocyte adhesion to the retinal vessels was more dependent on CD29 (the common chain of the beta 1 integrins) expression than either CD11a/CD18 or CD49d. CONCLUSIONS: This technique allows measurements to be made of lymphocyte adherence to vascular and nonvascular structures of retina ex vivo. Extension of this approach to the study of leukocyte adherence to sections of pathologic retina may be of clinical and experimental applicability in understanding mechanisms of retinal inflammation.

Intercellular adhesion molecule-1 in proliferative vitreoretinopathy.

PURPOSE: To measure vitreous levels of the soluble intercellular adhesion molecule (sICAM-1) in eyes with rhegmatogenous retinal detachment (RRD) complicated or uncomplicated by proliferative vitreoretinopathy (PVR) to investigate whether levels of this molecule related to history of previous retinal surgery or to the duration and severity of PVR. METHODS: The authors measured vitreous sICAM-1 by enzyme-linked immunosorbent assay in 28 eyes with PVR and 35 eyes with uncomplicated RRD. Vitreous from 10 eyes with macular holes and from 12 cadaveric eye donors were used as control specimens. RESULTS: Vitreous sICAM-1 levels were higher in the group with RRD complicated by PVR as a whole than in the group with RRD alone or in the control groups. In patients with no previous retinal surgery, there was no difference in vitreous sICAM-1 levels between the groups with RRD alone and RRD complicated by PVR. However, in patients who had undergone previous external surgery, those with PVR showed higher levels of vitreous sICAM-1 than those with RRD alone. In PVR, raised levels of sICAM-1 were associated preferentially with a history of previous vitrectomy as well as with a longer duration of the condition, although these levels were not related to the grade of PVR. In eyes with RRD alone, the levels of sICAM-1 were not enhanced with the duration of the detachment. Despite showing high vitreous levels of sICAM-1, patients with PVR did not exhibit increased serum levels of this adhesion molecule. CONCLUSIONS: The current observations suggest that those persons in whom PVR develops may have an impairment of the mechanisms that control the inflammatory response to retinal trauma. Persistently raised vitreous levels of sICAM-1 point to the continued operation of cytokine-mediated vascular reactions at the blood-retinal barrier.

Endothelial cell presentation of antigen to human T cells.

Activation of human T cells requires presentation of antigen by Ia (HLA-DR in man) bearing cells of the mononuclear phagocytic series (macrophages, MO, and more recently Langerhans cells, dendritic cells, and vascular endothelial cells. Since T cells must cross endothelial barriers to enter extravascular tissues during immune reactions, we investigated the role of endothelial cells in antigen presentation. Endothelial cells were cultured from human umbilical veins and identified by classic morphology and specific markers (factor VIII related antigen, and so on). Antigen-pulsed endothelial cells were used to present antigen to MO-depleted human T cells; activation was assessed by 3H-thymidine uptake. The HLA-DR compatible endothelial cells were as effective as MO in reconstituting MO-depleted T-cell responses. The endothelial cell reconstituted responses were antigen specific, HLA-DR restricted, and blocked by monoclonal antibodies to HLA-DR framework structures. Moreover, the T-cell responses were clonal with respect to HLA-DR. A monoclonal antibody completely eliminated MO reconstitution of the MO-depleted response without diminution of endothelial cell reconstitution of the same response. Fibroblasts and smooth muscle cells cultured from the same umbilical veins could not reconstitute the MO-depleted T-cell response. These data indicate that endothelial cells play an important and distinctive role in lymphocyte triggering.

Idiotypic characterisation of monoclonal antibodies with restricted epitope specificity for retinal S-antigen.

This paper describes the idiotypic specificities of eight murine monoclonal antibodies directed to three independent epitopes on retinal S-antigen. The antigenic sites recognised by these monoclonal antibodies have previously been localised to a small region near the C-terminal of bovine S-antigen. Xenogeneic, site-related anti-idiotypes prepared against each of the monoclonal antibodies recognised common idiotypes only amongst those monoclonal antibodies which reacted with the same epitope on S-antigen. Two of the three idiotypes were detected in the sera of BALB/c mice but not in two strains of rat immunised with xenogeneic S-antigen and none could be detected in the sera of patients with anti-photoreceptor autoantibodies. Our results demonstrate that the idiotypes of murine monoclonal antibodies to retinal S-antigen exhibit restricted epitope specificity but are species-restricted and imply that the S-antigen lacks a dominant antigenic epitope.

Differential effect of Bordetella pertussis on experimental posterior uveitis in the black-hooded Lister rat.

The effect of an additional adjuvant, Bordetella pertussis, on the clinical and histopathologic features of experimental autoimmune uveitis in black-hooded Lister rats was investigated. Disease was induced by a single footpad injection of purified retinal S-antigen in Freund's complete adjuvant. In those animals that did not receive B Pertussis the clinical features were those of a retinal vasculitis with disc edema, periphlebitis, and deep retinal infiltrates. In contrast, animals that received B pertussis developed lesions in the pigment epithelium and choroid. Histopathologic studies disclosed focal photoreceptor necrosis associated with mononuclear cell infiltration in both groups of animals. However, in the group that did not receive B pertussis the disease was predominantly a retinitis associated with perivascular infiltration of retinal vessels, whereas in the group that did receive B pertussis the main feature was a focal choroiditis, with superficial retinal lesions being rarely observed. Retinal photoreceptors were the target tissue in both groups of rats, but the route by which they were damaged was altered from predominantly retinal to choroidal by the addition of Bordetella pertussis as an adjuvant. This change may be ascribed to the ability of B pertussis toxin to sensitize vascular endothelium to local mast cell products, these cells being plentiful around choroidal vessels but absent in the retinal circulation.

A micro-method for peripheral leucocyte migration in tuberculin sensitivity.

Inhibition of buffy layer peripheral leucocyte migration by tuberculin purified protein derivative (PPD) from micro-capillaries mounted in small tissue culture chambers correlates in all cases with a positive Mantoux test. This quick and reproducible test of cellular hypersensitivity in man requires only 5-15 ml of blood and is applicable for study in children and in clinical situations where repeated monitoring of cellular immunity may be required.

Experimental autoimmune uveoretinitis in the RCS rat: the influence of photoreceptor degeneration on disease expression.

S-antigen induced experimental autoimmune uveoretinitis (EAU) was produced in the Royal College of Surgeons (RCS) strain of rat which develops a photoreceptor dystrophy within 2 weeks of birth. Animals were sensitised at 60, 90, and 105 days of age: all animals developed disease, but onset was significantly delayed in older (105 day) animals compared with those aged 60 days at sensitisation (p 0.003). Disease was characterised by the early development of complete serous retinal detachment which resolved in a few days: the prevalence of retinal detachment was increased to 80% in dystrophic animals compared with 10% in the congenic, non-dystrophic controls (p < 0.001). Anterior uveitis was seen in 17/30 control strain eyes, but in none of 30 dystrophic eyes (p < 0.001). Genetically determined photoreceptor and retinal pigment epithelium dysfunction in the RCS rat, which may involve the local accumulation of altered S-antigen, predisposes the dystrophic strain to display an acute retinal detachment in the early stages of EAU. This phenomenon illustrates how biochemical dysfunction of a target organ may influence susceptibility, form, and severity of an experimental autoimmune disease.

A longitudinal study of clinical and immunological findings in 52 patients with relapsing retinal vasculitis.

Fifty-two patients with retinal vasculitis--26 with idiopathic disease and 26 with associated systemic inflammatory disease--were followed up for periods ranging from six months to 12 years. The aim of the study was to determine the relationship between relapse of uveitis, visual outcome, and the occurrence of circulating immune complexes (CIC) and antiretinal antibodies. In a total of 69 relapses, CIC were increased in one-third of patients and antiretinal antibodies in one-half. In those 34 patients who expressed antiretinal antibodies 27 (79%) of the relapses were characterised by antiretinal antibodies in the absence of raised CIC levels (p less than 0.01). These findings support our previous hypothesis that CIC may have a protective role in autoimmune retinal vasculitis and that antiretinal autoimmunity is of pathogenetic importance in relapse. In individual patients the visual outcome was not related to the number of relapses or to the CIC-autoantibody pattern, suggesting the operation of additional features which merit identification.

Distribution of TNF alpha and its reactive vascular adhesion molecules in fibrovascular membranes of proliferative diabetic retinopathy.

AIMS: This study investigated the presence of the cytokine tumour necrosis factor alpha (TNF alpha) and the vascular adhesion glycoproteins ICAM-1, VCAM-1, E-selectin, P-selectin, and PECAM within fibrovascular membranes of eyes with proliferative diabetic retinopathy (PDR). METHODS: The presence of these molecules was determined by immunohistochemical staining using monoclonal antibodies and the APAAP technique. RESULTS: Staining for TNF alpha was observed on the retinal vascular endothelium of five of 12 specimens, on infiltrating cells within all membranes, and on the extracellular matrix of nine specimens. This staining wa abolished by absorption of the monoclonal antibody with human recombinant TNF alpha. Likewise, ICAM-1 staining was given by infiltrating cells and extracellular matrix of nine membranes and by the endothelium of three of the specimens. VCAM-1, E-selectin, and P-selectin staining was observed on the vascular endothelium of 5/12, 4/12, and 3/12 epiretinal membranes respectively. PECAM was expressed by the endothelium of 4/12 specimens, by infiltrating cells of 8/12 membranes, and also by the extracellular matrix of two of the specimens. CONCLUSION: The widespread distribution of TNF alpha and the nature of the adhesion molecules expressed by vascular endothelial cells in PDR membranes suggest that local activation of TNF alpha and enhanced expression of vascular cell adhesion molecules may play an important role in the development of the proliferative phase of diabetic retinopathy.

Human antiretinal antibodies in toxoplasma retinochoroiditis.

BACKGROUND/AIMS: Toxoplasma retinochoroiditis (TR) is an important cause of blindness and visual morbidity, affecting young adults. It has been postulated that some of the retinal damage observed in TR is due to antiretinal autoimmune mechanisms. METHODS: Humoral antiretinal autoimmunity in TR was investigated by indirect immunofluorescence (IIF) on normal human cadaveric retina and by a human retinal S-antigen ELISA. 36 patients with TR were separated on clinical grounds into those with first recurrence of disease (n = 18) or those with multiple recurrences (n = 18). Patients were also segregated into those with active (n = 28) or quiescent disease (n = 8). Serum from 16 normal controls (six with positive toxoplasma serology and 10 without) with no evidence of eye disease and 12 patients with idiopathic retinal vasculitis (IRV) were also tested. RESULTS: Sera from 34 of the 36 patients (94%) with TR demonstrated photoreceptor layer reactivity by IIF contrasting with six of 16 normal controls (p = < 0.001) and three of 12 IRV patients (p = < 0.001). Titres of antiphotoreceptor antibody were also higher among TR patients than controls. Sera from 27 of the 36 TR patients, 10 of 16 normals, and nine of 12 retinal vasculitis patients possessed anti-human retinal S-antigen antibodies at a titre of 1:400 or more as assessed by ELISA (p = > 0.05). Antiretinal autoantibody as detected by IIF did not run in parallel with S-antigen reactivity. CONCLUSIONS: The data indicate that the extent of antiretinal reactivity within TR is not accounted for by anti-S-antigen antibodies alone. This remarkably high prevalence of antiphotoreceptor antibody in TR as opposed to that found in either healthy or disease controls suggest that these antibodies may be co-pathogenic in toxoplasma retinochoroiditis.

A point prevalence study of 150 patients with idiopathic retinal vasculitis: 1. Diagnostic value of ophthalmological features.

This paper describes the ophthalmological features of 150 patients with idiopathic retinal vasculitis, 67 of whom had isolated retinal vasculitis (RV) and 83 had RV associated with systemic inflammatory disease (RV + SID). The diagnosis of retinal vasculitis was made by ophthalmoscopy and fluorescein angiography, and patients with any identifiable cause (infection, ischaemia, or malignancy) were excluded from the study. Patients with isolated RV tended to have peripheral vascular sheathing, macular oedema, and diffuse capillary leakage. Those with RV accompanying Behçet's disease often had branch vein retinal occlusions and retinal infiltrates together with macular oedema and diffuse capillary leakage; the retinal infiltrates were pathognomonic for Behçet's disease. In sarcoidosis the retina typically showed features of periphlebitis associated with focal vascular leakage. Patients with uveomeningitis, multiple sclerosis, arthritis, or systemic vasculitis showed diffuse retinal capillary leakage associated with a mixture of the other features. Poor visual function was particularly associated with macular oedema and branch vein retinal occlusion, while the retina appeared to 'withstand' the impact of vascular sheathing, periphlebitis, or neovascularisation alone. Within the limitations of a point prevalence study it was concluded that different patterns of retinal vasculitis occur in different systemic inflammatory diseases, and that in isolated retinal vasculitis there is a particular association between peripheral vascular sheathing, macular oedema, and diffuse capillary leakage. In Part 2 we describe the results of examining the sera of these patients for the presence of antiretinal antibodies and circulating immune complexes.

A point prevalence study of 150 patients with idiopathic retinal vasculitis: 2. Clinical relevance of antiretinal autoimmunity and circulating immune complexes.

This study describes the occurrence of antiretinal antibodies and circulating immune complexes in the sera of a large series of patients with idiopathic retinal vasculitis whose ophthalmological and clinical features are presented in Part 1. Antiretinal antibodies were measured by indirect immunofluorescence and passive haemagglutination, and circulating immune complexes were measured by polyethylene glycol precipitation and Clq binding. The occurrence of antiretinal antibodies and that of circulating immune complexes were analysed in relation to each other, to severity of retinal disease, to the type of associated systemic inflammatory disease, and to the presence of individual features of retinal inflammation. In patients with retinal vasculitis together with systemic inflammatory disease circulating immune complexes were usually accompanied by antiretinal antibodies. However, those patients with antiretinal antibodies in the absence of circulating immune complexes tended to have more severe retinal vasculitis, a feature particularly evident in Behçet's disease (p = 0.028). In patients with isolated retinal vasculitis, severity of disease was associated with antiretinal antibody (p = 0.013), as well as with the occurrence of both antiretinal antibody and circulating immune complexes together (p = 0.010). In the series as a whole there was a tendency for individual features of retinal vasculitis to be associated with antiretinal antibodies unaccompanied by circulating immune complexes; especially in macular oedema (p = 0.028). In isolated retinal vasculitis there was also an additive effect of antiretinal antibodies and circulating immune complexes in relation to disease severity; in contrast, in patients with systemic inflammatory disease, the coexistence of antiretinal antibodies and concluded that both antiretinal autoimmunity and circulating immune complexes may act as immunopathogenetic factors in idiopathic retinal vasculitis but that, in certain patients, circulating immune complex formation seems to protect against the more severe forms of autoimmune retinal inflammatory disease.

Experimental posterior uveitis. I: A clinical, angiographic, and pathological study.

The clinical, angiographic, and histopathological features of experimental posterior uveitis in the black hooded Lister rat are described. This mild form of experimental allergic uveoretinitis (EAU) is induced by sensitisation with retinal S antigen in Freund's complete adjuvant, and the inflammation produced is confined to the posterior segment of the eye. This allows for the first time precise photographic and angiographic documentation of the evolution of clinical signs, because there is minimal clouding of the vitreous by inflammatory cells. Clinically the disease is characterised by the appearance of disc oedema and periphlebitis, followed by focal infiltrates in the deep retinal layers, with eventual atrophy of the pigment epithelium. Histologically, retinal vasculitis is associated with focal mononuclear cell infiltration and necrosis of the photoreceptor layers. This model closely resembles the clinical features of idiopathic retinal vasculitis seen in man.