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• Background: Cellular mechanisms of inflammation are thought to be involved in the pathogenesis of proliferative vitreoretinopathy, and cytokines, which are products of cell activation, are known to play an important role in the development and maintainance of inflammatory reactions. It was the aim of this work to investigate the presence of cells expressing cytokine mRNA within retinal membranes. • Methods The presence of mRNA coding for the cytokines interleukin 1ß (IL-1ß), interleukin 6 (IL-6) and tumour necrosis factor a (TNFa) was investigated in 19 epiretinal membranes obtained from eyes undergoing vitrectomy for the treatment of retinal detachment complicated by proliferative vitreoretinopathy. • Results Cells expressing mRNA for IL-1ß were observed in 7 membranes, cells positive for IL-6 mRNA were seen in 12 membranes, and cells exhibiting mRNA for TNFa were present in 9 specimens. Only three membranes contained cells expressing mRNA for all the cytokines investigated. Four membranes possessed positive cells for IL-6 and TNFa, two contained cells expressing mRNA for IL-6 and IL-1ß, and two others exhibited cells expressing mRNA for TNFa and IL-1ß. Five membranes contained IL-6 mRNA-positive cells only, whilst two exhibited cells expressing mRNA for IL-1ß, or TNFa only. • Conclusion The present findings indicate that cellular activation may occur during the development of PVR, and suggest that these cytokines may be locally produced by cells infiltrating epiretinal membranes. The presence of IL-1ß, IL-6 and TNFa mRNA-positive cells within retinal membranes provides further evidence of a pathogenic role of these cytokines in proliferative vitreoretinopathy.

• Background: Epiretinal membranes from eyes with proliferative vitreoretinopathy (PVR) frequently express molecules associated with chronic inflammation. To investigate the extent to which inflammation may compromise the detached retina, we determined the expression of inflammatory molecules in anterior retina removed after relaxing retinotomy for retinal detachment complicated by anterior PVR. • Methods: Surgical retinal specimens were studied immunohistochemically for the distribution of the vascular cell adhesion molecules VCAM, E-selectin, P-selectin, ICAM and PECAM and for the presence of the cytokine TNFa and of T lymphocytes (CD3-positive cells), macrophages (CD68-positive cells) and HLA-DR molecules. The findings were compared with those in control cadaveric retina. • Results: Aberrant expresion of ICAM-1 was observed in four of nine retinal specimens from eyes with PVR, whereas its expression in control retinas was confined to the external limiting membrane and ganglion cell layers. PECAM was observed in seven of nine surgical retinal specimens and in four of five controls. E-selectin and P-selectin were expressed within the luminal aspects of four of nine retinal specimens from eyes with PVR, and VCAM was present in three of nine surgical specimens investigated. All cadaveric control retinas were negative for E-selectin and VCAM, whilst one was positive for P-selectin. Staining for TNFa was observed within luminal aspects and walls of retinal vessels from eight of nine surgical specimens, but was not seen in any of the cadaveric controls. T lymphocytes and cells expressing the macrophage marker CD68 were identified in two and seven of nine diseased retinas respectively, but not in any of the controls. Cells staining for HLA-DR were observed in eight of nine surgical retinal specimens and in three of five controls. • Conclusion: The present findings indicate that retina from eyes with advanced PVR may itself be subject to inflammatory changes, and indicate that the PVR process is not limited to retinal membranes, but involves a more widespread distribution of inflammation than is generally appreciated.

Prostaglandin production was studied in cultures of pig aorta endothelial cells using radioimmunoassay, radiochromatography, and smooth muscle bioassay. PGE2 was produced in higher concentrations than other prostaglandins. Bradykinin produced a rapid dose-related stimulation of PGE2 production. These results provided the basis for establishment of a simplified test system for investigating new compounds which alter prostaglandin synthesis and might therefore affect inflammatory responses. It was also observed that these endothelial cells do not metabolize prostaglandins via 15-hydroxyprostaglandin dehydrogenase.

The presence of interleukin 6 (IL-6), interleukin 1 (IL-1), interleukin 2 (IL-2) and tumour necrosis factor (TNF) was investigated in vitreous and aqueous aspirates from eyes undergoing vitrectomy for the treatment of different inflammatory conditions. Cadaveric vitreous from 10 normal subjects were used as controls. IL-6 was observed in 5 specimens from eyes with idiopathic uveitis (range = 26-264 pg/ml), in 2 specimens from eyes with uveitis complicated with retinal detachment (28 and 279 pg/ml, respectively), in 6 samples from eyes with diabetic retinopathy (range = 5-480 pg/ml), in one sample from an eye with phacolytic glaucoma (1190 pg/ml) and in one specimen from an eye with Behçet's disease (366 pg/ml). Although IL-1 was detected in 80% of all the samples investigated, concentrations of this cytokine >3 pg/ml were only observed in 2 specimens from eyes with uveitis (5 and 20 pg/ml, respectively) and 2 samples from eyes with diabetic retinopathy (3 and 31 pg/ml, respectively). TNF was present in 3 specimens from eyes with uveitis (range = 2-24 pg/ml) and 1 sample from eyes with diabetic retinopathy (4 pg/ml), but was not detected in the eyes with phacolytic glaucoma or Behçet's disease. IL-2 (≤0.1 U/ml) was detected in one sample from an eye with uveitis, one specimen from an eye with uveitis complicated with retinal detachment and 2 samples from eyes with diabetic retinopathy. None of the cytokines measured were detected in any of the control vitreous. The present observations suggest that cytokines, particularly IL-6 and IL-1, may act as local amplification signals in pathological processes associated with chronic eye inflammation.

A full-length cDNA clone to human S-antigen (HS-ag) was isolated from γgt 10 human retinal library and expressed as a fusion protein with glutathione S-transferase (GST) in E. Coli.Uveitogenicity and immunogenicity of recombinant GST-HS-ag fusion protein and native HS-ag were compared in EAU-susceptible Lewis rats.Recombinant HS-ag was found less uveitogenic than native HS-ag. Animals inoculated with recombinant HS-ag developed EAU on day 17, three days later than those inoculated with native HS-ag, the incidence of the disease was reduced from 80% to 58% and the score of clinical severity reduced from 2.2 to 1.3 points respectively. In contrast, rGST-HS-ag was more immunogenic than native HS-ag as it elicited four times higher levels of antibodies which reacted specifically with both antigens.

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.

Abstract: A morphological examination of synovial tissue from 25 patients with rheumatoid arthritis revealed that binucleated or multinucleated plasma cells were present in all samples and absent in synovia obtained from 16 control patients. Plasma cells containing two, three of four nuclei constitutet a mean 3% of the total plasma cell population. They were aways found amongst plasma cell infiltrates and in close association with small blood vessels. Ultrastructural analysis found no evidence of cellular membranes separating the individual nuclei in binucleated or multinucleated plasma cells, suggesting that the cells did not arise from fusion. Some of these plasma cells had a diameter approaching 100 µm, and many were in intimate contact with macrophages. The demonstration of a few cells with mitotic figures within the infiltrates suggests that the maintenance of plasma cell numbers in rheumatoid synovium may depend, in part, upon their local proliferation.

This study reports on the immunohistochemical staining for cytokine proteins of 26 epiretinal membranes obtained from eyes undergoing surgery for the treatment of proliferative vitreoretinopathy. All specimens were investigated for the distribution of staining for interleukin-lα (IL-lα), interleukin-1β (IL-1β), inter-leukin-6 (IL-6), tumour necrosis factor-α (TNFα), interferon-γ (IFNγ) and interleukin-2 (IL-2). The results showed that 22 of the membranes (85%) stained for TNFα not only intracellularly but also in the extracellular matrix. This contrasts with the findings that only 2 membranes stained for IL-lα and that another 3 were positive for IL-1β. Staining for the cytokines IL-6 and IFNγ was also observed in 9 and 7 membranes respectively. None of the specimens investigated stained with antibodies to IL-2 or control antibodies, and none of three normal retinas stained with any of the antibodies used. Pre-absorption of anti-cytokine antibodies with the corresponding human recombinant cytokines abolished staining of cells and extracellular matrix. The present findings support growing evidence that cytokine-mediated pathways of inflammation are involved in the pathogenesis of proliferative vitreoretinopathy, and draw attention to the possibility that interaction between extracellular matrix-bound cytokine and inflammatory leucocytes or resident cells of the retina may promote the development and perpetuation of this condition.

This paper addresses the molecular basis of interactions between leucocytes, other cells in the vitreoretinal environment and extracellular matrix that may underlie the pathogenesis of proliferative vitreoretinopathy. In this study we report the expression of adhesion molecules (CD11a, CD11c, CD18 and ICAM-1), lymphocyte surface markers (CD3, CD4, CD8 and CD22) and HLA-DR molecules in 25 epiretinal membranes obtained from eyes undergoing vitrectomy for the treatment of retinal detachment complicated by epiretinal membrane formation. Retinas from normal cadaveric eyes were used as controls. The results showed that cells expressing the adhesion molecules CD11a, CD11c and CD18 were present in 5 of 25, 17 of 25 and 11 of 23 membranes, respectively. Cells stained with antibodies against intracellular adhesion molecule 1 (ICAM-1) were observed in 24 of 25 membranes, whilst HLA-DR positive cells were seen in all membranes investigated. Immunohistochemical staining revealed that the molecules ICAM-1 or HLA-DR were not only expressed on inflammatory cells but also distributed within the extracellular matrix in several specimens. Lymphocytes expressing CD3 markers were present in 12 of 25 membranes, whilst T lymphocytes expressing CD4 and CD8 markers were observed in 5 of 18 and 12 of 24 membranes, respectively. In contrast, B lymphocytes expressing CD22 molecules were not found in any of the membranes. Leucocyte surface molecules were not expressed in control cadaveric retinas, although occasional cells expressing ICAM-1 were identified in the inner plexiform layer. The present findings indicate that selective interaction between infiltrating leucocytes and adhesion molecules present in extracellular matrix may well be involved in epiretinal membrane formation, and that T lymphocytes may play an important role in the pathogenesis of proliferative vitreoretinopathy.

We have investigated the expression of mRNA for interleukin 6 (IL-6) in cells infiltrating 12 epiretinal membranes, and the presence of biologically active IL-6 in vitreous humour available from five corresponding eyes. The results showed that nine of the 12 membranes (75%) contained cells expressing mRNA for this cytokine. Although in two of the specimens pigmented cells were identified as some of the cells expressing mRNA for IL-6, we did not identify the nature of IL-6 mRNA-producing cells infiltrating the membranes. Interestingly, two vitreous samples from eyes whose membranes did not contain cells with mRNA for IL-6 exhibited significant concentrations of IL-6 (315 and 28 μg/ml). Parallel study of mRNA for IL-6 in PVR biopsies and of IL-6 levels in corresponding vitreous may indicate how cytokine-mediated pathways of inflammation are involved in the pathogenesis of epiretinal membrane formation.

An immuno-electron microscopic analysis was undertaken to determine ICAM-1 expression on vascular endothelium in human tonsils and in synovia from patients with rheumatoid arthritis. ICAM-1 was preferentially expressed on high endothelial venules (HEV) located in the parafollicular regions of the tonsils and on HEV located in the villous processes of the synovia. On both tissues, these areas contained the greatest number of perivascular lymphocytes. In contrast, ICAM-1 was only weakly expressed on the low endothelium lining capillaries, venules and sinusoids. In both tonsils and synovia, ICAM-1 was confined to the luminal and lateral surfaces of the endothelial cells and absent from the abluminal surfaces adjacent to the basement membrane. We propose that in inflammatory tissues, ICAM-1 mediates the interaction of circulating lymphocytes with the high endothelial cells, but may not have a major role in promoting their migration through the whole thickness of the blood vessel wall.

Pretreatment of human monocytes with benoxaprofen for at least 2 h produced a dose-dependent abrogation of their adhesion to monolayers of cultured porcine endothelium with 0.05 μg/ml and 50.0 μg/ml of the drug inducing a mean 33% and 83% inhibition of adhesion respectively. When the endothelium was treated with the drug there was no modification of monocyte adhesion. In contrast, pretreatment of endothelium with 5.0 and 50.0 μg/ml benoxaprofen for at least 6 h, resulted in a mean 35% and 31% inhibition of polymorphonuclear cell (PMN) adhesion in 6/11 experiments. This inhibitory effect was not seen when drug-treated PMNs were added to endothelium. An impairment of monocyte chemotactic migration was only apparent with high concentrations of the drug (50 μg/ml). These results suggest that an important anti-inflammatory property of benoxaprofen is the inhibition of monocyte adhesion to vascular endothelium.

Four principal features of cellular immunity in the guinea-pig are mediated by a group of soluble factors generated by antigen-activated lymphocytes. These “lymphokines” are different from classical antibodies.

Blood monocytes from patients with RA exhibited a greater binding to monolayers of umbilical cord vein endothelium than monocytes from control subjects (mean 42% increase;p<0.01). When control monocytes were added to TNF or IL-1 treated endothelium their adhesion was enhanced (mean 24% increase;p<0.05), whereas the number of monocytes from RA patients binding to TNF or IL-1 treated monolayers was less than that adhering to untreated endothelial cells (mean 22% inhibition;p<0.02). The surface expression of CD11b/CD18 on RA monocytes was increased and pretreatment of normal and RA cells with an anti-CD18 monoclonal antibody inhibited their attachment to untreated and cytokine-treated endothelial cells. Normal blood monocytes activated with LPS demonstrated an enhanced binding to untreated cultures (mean 23% increase;p<0.05) and an inhibited attachment to cytokine-treated endothelial cells. This study suggests that blood monocytes in RA may be activated and that this property modifies the attachment of these cells to normal and “inflammatory” endothelium.

A soluble mediator is involved in the transformation of human lymphocytes by specific antigen.

THE cytotoxic effect on mouse ascites tumour cells treated in vitro with various antibodies has been shown to require the presence of complement1,2. In the absence of complement the cells appear to be normal when viewed by phase contrast microscopy3; they retain their capacity to exclude trypan blue2and to metabolize glucose4. The only changes which have been reported are slight alterations in the fine structure of the cell surface, which were thought to favour agglutination by rabbit antibody directed against ascites cells3.

RECENT emphasis has been placed on the lipid-protein composition of transplantation antigens derived from normal and neoplastic cells1and there is serological evidence for the occurrence of some of these antigens at cell surfaces2,3. The presence of transplantation antigens outside the nucleus of a cell implies the operation of a mechanism whereby the genetic individuality of nuclear components is expressed in cytoplasmic materials which are characteristic of the individual.