Immunology and growth characteristics of ocular basal cell carcinoma.

BACKGROUND: Knowledge about immunological features and growth characteristics of palpebral (ocular) basal cell carcinomas (BCCs) is limited. In particular, it is unclear whether ocular BCC represents in this regard a special BCC entity or not. METHODS: Twenty BCCs of the lid area (ocular BCCs) were investigated immunohistologically using monoclonal antibodies against CD4, CD8, CD45Ro, CD50, CD68, HECA-452, Ki67 (MIB1), and the p53 epitope. For comparison, nine BCCs excised distant from the eye (non-ocular BCCs) were evaluated. RESULTS: In BCCs the distribution of the immunocompetent cells investigated is markedly irregular. These cells are localized mainly around BCC islands. Only a few of them invade tumour cell aggregates. The CD4:CD8 ratio as detected by immunohistochemistry is >1 in 82% of ocular BCCs and in 88% of nonocular BCCs. Often there are dense infiltrations of CD68+ cells (macrophages) and HECA-452+ cells adjacent to tumour cell aggregates. The growth fraction [percentage of proliferating (Ki67+/MIB 1+) cells] varies from 0% to more than 30%. Proliferative activity is enhanced at the invasion front. Additionally, the amount of p53+ cells differs considerably among the BCCs. CONCLUSIONS: CD4+ T cells seem to be the most important cell population for BCC immunosurveillance, offering the chance for conservative interferon therapy. The role of CD68+ and HECA-452+ cells has to be further elucidated. In many tumours the large amount of proliferating cells contrasts to the usually slow growth of BCCs, indicating strong apoptotic processes. The results can be regarded only as semiquantitative. So far, ocular and nonocular BCCs exhibit no essential differences regarding immunocompetent cell infiltration and growth characteristics. According to this, palpebral BCCs are "normal" BCCs and not a special BCC variant. Therefore, results from dermatological research concerning BCC can be extended without limitations to their counterparts in the lid area.

Identification of visual arrestin (S-antigen) in retinal pigmented epithelial cells.

PURPOSE: Inactivation of photolyzed rhodopsin requires phosphorylation of this receptor and binding of the 48 kDa regulatory protein arrestin (S-antigen). Arrestin is also to cause an autoimmune disease, uveoretinits, that resembles uveitis in humans. In this study we demonstrate the presence of visual arrestin in retinal pigment epithelial cells (RPE) in culture. METHODS: Bovine RPE were isolated. Mouse and rat monoclonal and rabbit polyclonal antibodies against visual arrestin, and a synthetic peptide "GFLGELTSSEVATEVPFRLM" (a pathogenic sequence corresponding to residues 340 to 359 of human visual arrestin), and rabbit polyclonal antibody against the specific peptide "EDPDTAKESFQ" for bovine visual arrestin were used to detect arrestin in RPE cells. Using visual arrestin specific primer, RT-PCR of RNA from RPE was performed. RESULTS: By western blots analysis a 48 kDa protein, corresponding to visual arrestin was detected with both mAb and polyclonal antibodies in extracts of RPE cells. RT-PCR analysis of RNA from RPE cells confirmed the presence of arrestin mRNA of predicted 377 bp and exhibited 100% homology with visual arrestin 48 kDa. CONCLUSION: Visual arrestin proteins present in RPE may be involved in the desensitization of G-protein-coupled receptors in RPE cells and in arrestin uveopathogenesis.

[Experimental autoimmune uveitis. Characterization of retina infiltrating cells]. / Experimentelle Autoimmun-Uveitis. Charakterisierung der die Retina infiltrierenden Zellen.

UNLABELLED: The chronic model of murine EAU induced by interphotoreceptor retinoid binding protein represents a disease similar to clinical chorioretinitis. In this study we characterized the kinetics of retina infiltrating T-cells, macrophages and expression of the adhesion molecules ICAM-1 and ICAM-2. METHODS: B10.A mice were immunized subcutaneously with IRBP, and the eyes were analyzed on days 10, 18, 24 and 28. The infiltrating cells were characterized by mAbs recognizing T-cell receptors (TCR) Vss6 and Vss8, T-cell markers, macrophages and ICAM-1 and ICAM-2. RESULTS: While CD8+ T-cells and ICAM-2 were detectable from day 10 (retina is intact) until day 28, CD4+ T-cells, macrophages and ICAM-1 appear with the onset of retinal destruction. Starting at day 10 the dominating TCR was Vss6; Vss8 was noticed from day 18 on. CONCLUSION: CD8+ T-cells infiltrating the intact retina and stimulating the expression of high endothelial venules (HEVs) could be responsible for the onset of uveitis.

[High endothelial venules. Kinetics of the expression in IRBP-induced experimental autoimmune uveitis]. / High Endothelial Venules. Kinetik der Expression in der IRBP-induzierten experimentellen Autoimmunuveitis.

UNLABELLED: Experimental autoimmune uveitis (EAU) is a T-cell-mediated disease expressing high endothelial venules (HEVs) in the retina. HEVs could be responsible for the absorption of activated T-cells. The purpose of this study was to investigate the kinetics of HEV expression in the murine IRBP (interphotoreceptor retinoid binding protein) induced EAU. METHODS: B10. A mice were immunized subcutaneously with IRBP. The eyes were analysed on days 10, 18, 24 and 28 (n = 5 for each time point). While HEVs were identified with the mAb MECA 325, the control mAb MECA 20 stained all endothelial cells. RESULTS: HEVs were detectable in the intact retina from day 10. Presence of HEVs peaked on day 18 and decreased by day 28, when maximal inflammation and retinal destruction was detectable. CONCLUSION: HEV expression could play a central role in the onset of EAU, allowing homing and migration of inflammatory cells into the eye.

[Physiological protective mechanisms of the eye]. / Physiologische Schutzmechanismen des Auges.

The physiological mechanisms for the protection of the eye are only partly known. It becomes increasingly evident that the eye is supervised by and included in the immune system of the body. The physiological protection system of the eye consists of a mechanical and an immunological component. The lacrimal gland plays a key role for the immune system of the anterior segment. It is part of the MALT system, and the characterisation of the special ocular components of this system-including possible homing receptors-will give important informations. Research of the ocular immune system has disclosed various special features, like the anterior chamber associated immune deviation (ACAID). The distribution of antigen presenting cells and its localization, but also the distribution of T- and B-lymphocytes is an important factor for limiting ocular inflammation. The phenomenon of 'apoptosis' seems to have an important role in maintenance of the ACAID. The cornea is nearly free of cells, and infiltrating antigen presenting cells may prevent ACAID. Research regarding mechanisms which are used to tuned these various cells will give answers to the questions how the cornea contains its optical transparency, how corneal transplant rejection works, how the eye participates in systemic disorders and may also define the role of a possible dysfunction of antigen presenting cells of the retinal pigment epithelium in senile maculopathy.

Immunological characterization of an immunomodulatory epitope in S-antigen/arrestin with a sequence motif common to tumor necrosis factor alpha.

Some monoclonal antibodies (mAbs) to retinal S-antigen recognize a phylogenetically conserved epitope (S2) in the N-terminal part of the protein. These antibodies have been shown to inhibit the induction of experimental autoimmune uveoretinitis by S-antigen in rats. Using Pepscan method, we localized this epitope on the amino acid (aa) residues 40-50, i.e., PVDGVVLVDPE (peptide S2). MAb binding was confirmed by ELISA, competition-ELISA and dot blot. Other S-antigen peptides with homologies to epitope S2 and peptides exhibiting the pathogenic and T-cell proliferation inducing sites did not bind these mAbs. Epitope S2 displays an immunological crossreactivity with human tumor necrosis factor (TNF) alpha. Recent results indicate that both peptide S2 and a peptide from human TNF alpha (aa residues 31-53) containing the common sequence motif GVxLxD induce TNF alpha production in monocytes. We analyzed the fine structure of the common epitope by studying mAb binding in an amino acid residue exchange experiment.

A common epitope on human tumor necrosis factor alpha and the autoantigen 'S-antigen/arrestin' induces TNF-alpha production.

A common epitope on S-antigen (arrestin), a potent autoantigen inducing experimental autoimmune uveoretinitis (EAU), and on human tumor necrosis factor alpha (hTNF alpha) was revealed using two monoclonal antibodies to S-antigen which inhibit EAU induction. The minimal common sequence for monoclonal antibody recognition is GVxLxD in the S-antigen/hTNF alpha amino acid sequences. Peptides containing this sequence motif exhibited monocyte activating capacity similar to the autocrine stimulatory capacity of hTNF alpha itself. In the S-antigen this activity was located from residue 40 to 50, corresponding to the peptide PVDGVVLVDPE (epitope S2). In hTNF alpha, the monocyte activating capacity correlated to residue 31 to 53, corresponding to the peptide RRANALLANGVELRDNQLVVPSE (peptide RRAN). The identified regions define common functional structures in the autoantigen and in the hTNF alpha molecule. The data suggest a regulatory function of this particular structure in TNF alpha expression and in autoimmunity.

Humoral immune response against the S-antigen/TNF alpha common epitope in rat EAU suppressed by the monoclonal antibody S2D2.

S-antigen (S-Ag)-induced experimental autoimmune uveoretinitis (EAU) in rats can be suppressed by injecting the mouse monoclonal antibody (mAb) S2D2 or a polyclonal rat anti-idiotype S2D2 (anti-Id S2D2) antibody, the internal image of the epitope of S-Ag recognized by mAb S2D2. This epitope located in amino acids 40-50 of bovine S-Ag (peptide S2), displays an homology with a sequence of human tumor necrosis factor alpha (hTNF alpha) (peptide RRAN) which is also recognized by S2D2. (Stiemer et al., this symposium). We show that one injection of S2D2 at the time of immunization with S-Ag suppressed EAU and modulated the production of antibodies against peptides of bovine or human S-Ag containing the S2 epitope and against peptide RRAN. Immunization against anti-Id S2D2 stimulated antibody production to peptide S2 and RRAN and inhibited EAU. These data suggest that disease suppression could be related to the production of antibodies against the S-Ag/TNF alpha common epitope.

Cytokine induction by immunomodulatory epitopes in S-antigen and tumor necrosis factor alpha.

Common epitopes on S-antigen (arrestin), a potent autoantigen inducing experimental autoimmune uveoretinitis (EAU), and on human tumor necrosis factor alpha (hTNF alpha) are revealed with monoclonal antibodies (mAb) to S-antigen, which inhibit EAU induction. The minimal common sequence for mAb recognition is GVxLxD in the S-antigen/hTNF alpha amino acid (aa) sequences. Peptides containing this sequence motif exhibit monocyte activating capacity analogous to the autocrine stimulatory capacity of hTNF alpha itself. In S-antigen this activity is located at epitope S2 (aa residues 40 to 50), corresponding to the peptide PVDGVVLVDPE (peptide S2). In hTNF alpha the monocyte activating capacity correlates to aa residue 31 to 53, corresponding to the peptide RRANALLANGVELRDNQLVVPSE (peptide RRAN). Peptide S2 but not peptide RRAN is competing for mAbs S6H8 and S2D2 binding to S-antigen. Anti-idiotypic antibodies to S2D2 compete with peptide S2 but not peptide RRAN for binding to mAbs S2D2 and S6H8. In human retinal S-antigen epitope S2 is localized at the aa residues 44-54 and is cleaved in the human peptide 4 (aa 31-50). Competition experiments with peptide 4 (aa 31-50) and peptide 5 (aa 41-60) indicate that the C-terminal aa residues VDPD in the epitope S2 play an important role for internal image recognition of the anti-idiotypic antibodies. Peptide S2 and peptide RRAN define common functional structures in the autoantigen and hTNF alpha molecules. The data suggest regulatory functions of the peptides in cytokine expression, network regulation and in autoimmunity.