Pegylated interferon-α-2b reduces corticosteroid requirement in patients with Behçet's disease with upregulation of circulating regulatory T cells and reduction of Th17.

OBJECTIVE: To determine whether the addition of 26 weeks of subcutaneous peginterferon-α-2b could reduce the requirement for systemic corticosteroids and conventional immunosuppressive medication in patients with Behçet's disease (BD). METHODS: We conducted a multicentre randomised trial in patients with BD requiring systemic therapy. Patients were randomised to 26 weeks of peginterferon-α-2b in addition to their standard care or to standard care only and followed 6-monthly for 3 years with BD activity scores and quality of life questionnaires. Patients at one centre had blood taken to measure regulatory T cells (Tregs) and Th17 cells. RESULTS: 72 patients were included. At months 10-12, while among the entire patient population there was no difference in the corticosteroid dose or immunosuppression use between the treatment groups (adjusted OR 1.04, 95% CI 0.34 to 3.19), post hoc analysis revealed that in patients who were on corticosteroids at baseline the corticosteroid requirement was significantly lower in the peginterferon-α-2b (6.5 (5-15) mg/day) compared with the non-interferon group (10 (8.25-16.5) mg/day, p=0.039). Furthermore, there was a trend towards an improved quality of life that became significant by 36 months (p=0.008). This was associated with a significant rise in Tregs and a decrease in Th17 cells which was still present at 1 year and 6 months after the interferon was stopped. The safety profile was similar with adverse events in 10% in both groups. CONCLUSIONS: The addition of peginterferon-α-2b to the drug regime of BD patients did not significantly reduce their corticosteroid dose required at 1 year. However, in those on corticosteroids at baseline post hoc analysis demonstrated that the addition of peginterferon-α-2b did result in a significant reduction in corticosteroid dose with a significantly improved quality of life and trend to reduce other required immunosuppressive agents. This effect was seen at 1 year and associated with a rise in Tregs suggesting a possible mode for interferon action. TRIAL REGISTRATION NUMBER: ISRCTN 36354474; EudraCT 2004-004301-18.

Lymphocyte adhesion to cultured endothelial cells of the blood-retinal barrier.

Microvascular endothelial cells derived from the blood-retinal barrier were grown in vitro and various factors affecting the adhesion of syngeneic lymphocytes to these monolayers was evaluated. Under resting conditions 5.3 +/- 0.4% of lymphocytes derived from peripheral lymph nodes (PLN) were found to adhere to the endothelia. Adhesion of resting lymphocytes increased significantly following endothelial treatment with interferon-gamma (IFN-gamma; 11.7 +/- 1.0%), interleukin-1 (IL-1; 14.9 +/- 1.2%), astrocyte conditioned medium (ACM; 12.7 +/- 0.9%) or forskolin (13.9 +/- 1.2%). Lymphocyte activation with concanavalin A (ConA) increased adhesion to 17.0 +/- 0.9% which could be augmented by activating the endothelia with IFN-gamma (22.3 +/- 1.0%), IL-1 (24.0 +/- 1.0%) and ACM (25.7 +/- 1.6%). An antigen-specific CD4+ T cell line exhibited the greatest degree of adhesion, 40.4 +/- 2.5% on resting endothelia, 60.0 +/- 3.0% on IFN-gamma-activated cells and 54.3 +/- 1.4% on IL-1-activated cells. Although CD4+ lymphocytes predominated in the PLN population by 2:1, significantly more CD8+ cells were found to adhere.

Antigen presentation by rat brain and retinal endothelial cells.

Brain and retinal endothelial cells (EC) form the blood-brain and vascular blood-retinal barriers, respectively, and are believed to play a role in mediating T cell responses in the central nervous system. In this study, Lewis rat retinal and brain EC grown in vitro were capable of expressing MHC class II I-A but not I-E molecules following treatment with interferon-gamma. In the presence of their antigen, CD4+ antigen-specific T cells were able to mediate lysis of retinal EC monolayers to a similar extent as brain EC. T cell proliferation was poorly supported by confluent retinal or brain EC monolayers, but subconfluent EC monolayers supported proliferation in a MHC class II (I-A)-restricted manner (P < 0.001). Exposure of T cells to confluent retinal EC monolayers resulted in them becoming less responsive to subsequent antigen presentation by thymocytes. Conversely, pre-exposure with subconfluent EC had no such effect. These results suggest that a non-proliferating EC monolayer is able to downregulate T cell responsiveness which may have important implications during lymphocyte traffic across the blood-tissue barriers of the central nervous system.

SV40 large T immortalised cell lines of the rat blood-brain and blood-retinal barriers retain their phenotypic and immunological characteristics.

In the central nervous system the blood-brain and blood-retinal barriers (BBB and BRB respectively) are instrumental in maintaining homeostasis of the neural parenchyma and controlling leucocyte traffic. These cellular barriers are formed primarily by the vascular endothelium of the brain and retina although in the latter the pigmented epithelial cells also form part of the barrier. From primary cultures of rat brain endothelium, retinal endothelium and retinal pigment epithelium (RPE) we have generated temperature sensitive SV40 large T immortalised cell lines. Clones of brain (GP8.3) and retinal (JG2.1) endothelia and RPE (LD7.4) have been derived from parent lines that express the large T antigen at the permissive temperature. The endothelial cell (EC) lines expressed P-glycoprotein, GLUT-1, the transferrin receptor, von Willebrand factor and the RECA-1 antigen and exhibited high affinity uptake of acetylated LDL and stained positive with the lectin Griffonia simplicifolia. The RPE cell line was positive for cytokeratins and for the rat RPE antigen RET-PE2. All the cell lines expressed major histocompatibility complex (MHC) class 1 and intercellular adhesion molecule (ICAM)-1 constitutively and could be induced to express MHC class II and vascular cell adhesion molecule (VCAM)-1 following cytokine activation. The EC also expressed platelet endothelial cell adhesion molecule (PECAM)-1. Monolayers of these cells could support the migration of antigen-specific T cell lines. The generation of immortalised cell lines derived from the rat BBB and BRB should prove to be useful tools for the study of these specialised cellular barriers.

The immunomodulatory effect of topical cyclosporin A in atopic keratoconjunctivitis.

PURPOSE: To perform a detailed examination of the immunomodulatory effects of topical cyclosporin A (CsA) in conjunctival tissue from patients with atopic keratoconjunctivitis (AKC). METHODS: Patients with active AKC were randomly allocated into two groups of four patients. For 3 months one group received 2% CsA drops, and the other group received placebo drops. Superior tarsal conjunctival biopsy specimens were harvested before and after treatment and examined by one- and two-color immunohistochemistry to compare leukocyte counts, HLA-DR+ and IL-2R+ cell counts, HLA-DR positivity of conjunctival epithelial cells, and counts of T cells expressing the cytokines interleukin (IL)-2, IL-3, IL-4, IL-5, and interferon (IFN)-gamma. RESULTS: Posttreatment values were significantly less than pretreatment values for the total number of leukocytes and in the numbers of CD3+ T cells, CD4+ cells, CD8+ cells, CD20+ B cells, neutrophils, and macrophages, and there was a decrease in the CD4-CD8 ratio (P = 0.03) in the CsA group. There was a reduction from before CsA treatment to after CsA-treatment in the numbers of HLA-DR+ and IL-2R+ cells (P = 0.03), but the reduction in the epithelial cell HLA-DR expression did not reach significance. The number of T cells staining for IL-3 and IL-5 was reduced, although not to statistical significance, but there was a significant reduction in the number of T cells expressing IL-2 and IFN-gamma (P = 0.03) after CsA treatment compared with initial values. There were no statistically significant differences between pretreatment and posttreatment values in the placebo group. There was a clinical improvement in the CsA group and a clinical worsening in the placebo group. CONCLUSIONS: The in vitro effects of CsA translate into a reduction in T cells, a normalization of the CD4-CD8 ratio, a decrease in T-cell activation, and a reduction in T-cell cytokine expression, especially IL-2 and IFN-gamma. The decrease in HLA-DR expression may be mediated by the change in IFN-gamma. There were fewer B cells but not fewer plasma cells after CsA and no change in IL-4 expression, suggesting minimal effects on type I hypersensitivity responses. There was no significant reduction in mast cell or eosinophil numbers, but direct effects of topical CsA on their function may play a role in the therapy of ocular allergic disease. These results show that the beneficial effects of topical CsA in AKC are accompanied by important changes in conjunctival immune cell profiles.

Increased CD4+ expression and decreased IL-10 in the anterior chamber in idiopathic uveitis.

PURPOSE: To compare cell types and cytokines in aqueous humor from patients with uveitis either occurring in association with a systemic disease or apparently isolated and not associated with a systemic disease. METHODS: Cells were collected by centrifugation of fresh aqueous humor from uveitis and controls, and immunofluorescence techniques were performed with markers for T cells, B cells, and monocytes. Cytokines were measured in the aqueous supernatants, and serum samples were assayed for soluble interleukin-2 receptors. RESULTS: When aqueous samples from idiopathic uveitis were compared with those from uveitis associated with a systemic disease, there were increases in CD3+, CD4+ (p = 0.001), and activated CD4+ T cells (p = 0.02) and a decrease in B cells (p = 0.0013). This was not reflected in the peripheral blood where there were no differences in the cell types or in soluble interleukin-2 receptor levels. No cells were obtainable from control aqueous. Interleukins-10 and -12, interferon-gamma, and transforming growth factor-beta2 were detected in aqueous supernatants. Interleukin-10 was reduced (p = 0.024) in uveitis in comparison with controls. CONCLUSIONS: The results suggest a selective recruitment of CD4+ T cells within aqueous humor but only in idiopathic uveitis. In both disease groups there was a decrease in the immunoregulatory cytokine interleukin-10, which might enable an immune response to occur in an otherwise highly immunosuppressive microenvironment. Increases in activated CD4+ T cells combined with depressed interleukin-10 levels could partially explain why, for example, in acute anterior uveitis, the inflammatory disease is often more severe.

Role of tumour necrosis factor-alpha in dendritic cell-mediated primary mixed leucocyte reactions.

Tumour necrosis factor (TNF alpha) is a major inflammatory cytokine with potentiating effects on specific immune responses, including graft-versus-host disease. This study examined the contribution of TNF alpha to dendritic cell (DC)-mediated primary allogeneic T lymphocyte responses. Purified blood DC were shown to produce minimal amounts of TNF alpha mRNA but no significant TNF biological activity or secreted TNF alpha as measured by ELISA. Amplification of DC mRNA by PCR using oligonucleotide primers to CD120a (TNFRI, p55) and CD120b (TNFRII, p75) and probing with specific internal oligonucleotides, suggested that DC express the CD120b but little if any CD120a. These results were confirmed using monoclonal antibodies to the TNF receptors. Polyclonal antiserum specific for TNF alpha blocked the blood DC-stimulated allogeneic mixed leucocyte reaction (MLR). The addition of TNF alpha to suboptimal MLRs (limited DC stimulators), increased the proliferation of responding T lymphocytes. Having confirmed that T lymphocytes produce TNF alpha and express CD120b after stimulation, we sought to clarify whether the contributing effect of TNF alpha to the allogeneic MLR resulted from a TNF alpha-mediated signal stimulating DC activity, or as a result of autocrine stimulation of T lymphocytes. Pre-incubation of DC with TNF alpha did not increase DC stimulatory capacity and late addition of anti-TNF serum (up to 72 h) still had a significant inhibitory effect on the MLR. We conclude that TNF alpha is probably not involved in the initial DC-T lymphocyte interaction, but acts as an autocrine growth factor for DC induced T lymphocyte proliferation.

Superoxide dismutase (glu100-->gly) in a family with inherited motor neuron disease: detection of mutant superoxide dismutase activity and the presence of heterodimers.

Superoxide dismutase glu100-->gly, a mutation known to be associated with familial motor neuron disease (familial amyotrophic lateral sclerosis) has been detected in one symptomatic and five of seven asymptomatic members of a family with a history of this disease. On average, the individuals with the mutation had 75% of normal red blood cell superoxide dismutase activity. Native polyacrylamide gels stained for superoxide dismutase activity showed two abnormal bands in the family members identified as carrying the mutation. This indicates that active mutant enzyme is present in red cells and forms stable homodimers and heterodimers with the normal chain. A silent mutation in exon 4, not associated with motor neuron disease, was also detected in one family member.

Distribution of IL-2R and CD45Ro expression on CD4+ and CD8+ T-lymphocytes in the peripheral blood of patients with posterior uveitis.

Different lines of evidence support a major role for activated T-lymphocytes in the pathogenesis of posterior uveitis. The initial site of activation of these autoreactive T-cells, either locally in the eye or in the peripheral immune compartment, is still unknown. This study was undertaken to investigate whether with currently available techniques, it is possible to detect alterations in the levels and subsets of activated T-cells in the peripheral blood of patients with posterior uveitis. For this reason, 3-colour immunofluorescent staining was performed to assess the distribution of IL-2 receptors (IL-2R) and the CD45RO-antigen on CD4+ and CD8+ subsets of peripheral blood lymphocytes (PBLs) from patients with posterior uveitis (n = 29). Only the subgroup of patients with posterior uveitis as part of a systemic immune-mediated disease (sarcoidosis, Behçet's disease) (n = 9) showed a significant increase in IL-2R expression on peripheral blood lymphocytes (p less than 0.005) when compared to normals (n = 12). This increased expression was reflected much more significantly in the CD4+ (p less than 0.0005) rather than in the CD8+ subset (p less than 0.05) of lymphocytes. In contrast, no significant increase in CD45RO expression on either subset of T lymphocytes was found in any subgroup of posterior uveitis in comparison with normals.

Multiple cytokines in human tear specimens in seasonal and chronic allergic eye disease and in conjunctival fibroblast cultures.

BACKGROUND: Several cytokines are involved in the recruitment and activation of inflammatory cells in ocular allergic diseases. The purpose of the study was to assay multiple cytokines and chemokines in tears, to compare subgroups of allergic conjunctivitis (AC) with controls, and in culture supernatants to determine whether conjunctival fibroblasts produce some of these cytokines. METHODS: Fifty to one hundred microlitre tears were obtained from patients with active seasonal allergic conjunctivitis (SAC; n=12), vernal keratoconjunctivitis (VKC; n=18), atopic keratoconjunctivitis (AKC; n=6) and non-atopic controls (n=14). Primary conjunctival fibroblasts grown in vitro were stimulated with IL-4, IL-13 or TNF-alpha for 24 h. Cell-free tear and culture supernatants were assayed for IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, IFN-gamma, TNF-alpha, eotaxin, MCP-1 and RANTES using multiplex bead analysis. Induction of chemokine gene expression was determined by PCR. RESULTS: IL-1beta, IL-2, IL-5, IL-6, IL-12, IL-13, MCP-1 were increased in all tears groups compared with controls, with highly significant correlations between many of these molecules. In addition IL-4, IFN-gamma, and IL-10 were elevated in SAC and VKC, while eotaxin and TNF-alpha were only increased in VKC. IL-6, IL-8, MCP-1, RANTES and eotaxin were detected from fibroblasts cultures, and were all up-regulated by TNF-alpha. By PCR, fibroblasts expressed MCP-1 transcripts constitutively, whereas IP-10 and Mig were up-regulated by TNF-alpha. CONCLUSIONS: Differential cytokine levels support tears as a useful indicator of immune mechanisms occurring during AC. The striking similarities in chemokine profiles between tears and fibroblasts suggest these cells as likely sources of chemokines in tears.

Lymphocyte migration through cultured endothelial cell monolayers derived from the blood-retinal barrier.

Lymphocyte migration across endothelial monolayers, derived from the rat blood-retinal barrier, was recorded in vitro using time-lapse video microscopy. Syngeneic lymphocytes were plated out onto endothelial cell monolayers for 4 hr and their surface motility and transmonolayer migration recorded and quantified. Under resting conditions lymphocytes, obtained from peripheral lymph nodes (PLN), were small, rounded and static with less than 5% migrating across the monolayer. Activation of the lymphocytes with concanavalin A (Con A) increased their size and surface motility on both interferon-gamma (IFN-gamma)-treated and resting endothelia, but did not alter the number migrating across the monolayer. Similar results were also found for phytohaemagglutinin (PHA)-activated lymphocytes. Interleukin-2 (IL-2)-dependent CD4+ T-cell lines specifically recognizing either retinal soluble antigen (S-Ag) or bovine serum albumin (BSA) exhibited significantly greater surface motility over the endothelial monolayers than the mitogen-activated PLN lymphocytes. By 4 hr, in excess of 50% of the T-cell line lymphocytes had migrated across the endothelial monolayer. Treatment of the endothelial cells with IFN-gamma caused a small, but not significant, increase in the level of T-cell line lymphocyte migration. These results suggest that the migration of lymphocytes across central nervous system-derived endothelia is primarily dependent upon the state and mode of lymphocyte activation.

Nucleotide sequence analysis of the movement genes of resistance breaking strains of tomato mosaic virus.

The nucleotide sequences were determined for the movement genes, encoding 30K proteins, of two resistance breaking strains of tomato mosaic virus (ToMV), LII-ToMV and LIIA-ToMV. The putative amino acid sequences of the encoded proteins were compared with L-ToMV and with two previously published resistance breaking strains, Ltb1-ToMV and C32-ToMV. LII-ToMV, a Type 2 strain able to infect tomatoes containing the Tm-2 gene, has four amino acid changes relative to L-ToMV. One of these substitutions, Glu-Lys133, is also found in the other Type 2 strains, Ltb1-ToMV and C32-ToMV. LIIA-ToMV, a Type 2(2) strain able to overcome the resistance conferred by the tomato Tm-2(2) gene, has four amino acid differences from L-ToMV. The Type 2(2) strain has no substitutions in common with any of the Type 2 strains; however the predominance of amino acid substitutions that involve a change in the local charge (six out of the eight) suggests an electrostatic interaction between a host factor and the 30K protein may be intrinsic to the function of the movement gene and/or resistance breakage.

Experimental autoimmune uveoretinitis (EAU) versus experimental allergic encephalomyelitis (EAE): a comparison of T cell-mediated mechanisms.

EAU is a model of ocular inflammatory disease. EAU resembles another T cell-mediated autoimmune disease--experimental allergic encephalomyelitis--since both have increased expression of MHC class II molecules in the target tissue, can be adoptively transferred by activated CD4+ T cells and are inhibited by cyclosporin A. The immunological findings will be compared to find out if the same cellular mechanisms are involved in both diseases.

Oligoclonal activation of CD4+ T lymphocytes in posterior uveitis.

Several lines of evidence support an important role for activated T lymphocytes in the perpetuation of autoimmune intraocular inflammatory disease (posterior uveitis). In this study peripheral blood lymphocytes (PBL) were examined by three-colour flow cytometry to assess the distribution of IL-2 receptors (IL-2R) among CD4+ and CD8+ T cell subsets in patients with active posterior uveitis and control subjects. Patients with uveitis (n = 70) showed a significant increase in PBL expressing the alpha-chain (Tac) of the IL-2R compared with controls (n = 28) (34.2% versus 29.6%) (P < 0.05). This increased Tac expression was present on both the CD4+ subset (25.7% versus 20.9%) (P < 0.05) and the CD8+ subset (2.5% versus 1.8%) (P < 0.05) of lymphocytes. We also examined whether the activated CD4+ PBL from uveitis patients (n = 30) showed a dominant pattern of T cell receptor (TCR) gene rearrangement, suggestive of an oligoclonal response to a small number of antigenic peptides. A significant increase in the usage of the V alpha 2.3 TCR family by activated but not by non-activated CD4+ PBL was detected in patients (3.9% versus 3.4%) (P < 0.05) compared with controls. There was evidence of oligoclonal activation of CD4+ PBL in 11/30 patients (36.7%) but in none of the controls (n = 10). However, different V alpha or V beta TCR families were selectively activated among and even within individual patients. The heterogeneity in TCR expression among patients with active intraocular inflammatory disease is discussed.

Isolation of retinal lymphocytes in experimental autoimmune uveoretinitis: phenotypic and functional characterization.

Lymphocytes were obtained from the inflamed retinas of Lewis rats with S antigen (S-Ag)-induced experimental autoimmune uveoretinitis (EAU). In early disease 81% of these were CD4+ T cells. Thirty-four per cent of retinal CD4+ T cells expressed the interleukin-2 receptor (IL-2R) and 95% were CD45R-. These phenotypes contrast sharply with those of peripheral blood and lymph node CD4+ T cells isolated from EAU rats and confirm a high level of CD4+ T-cell activation in the retina in early disease. Although the relative proportions of CD8+ T cells increased in late disease, so did those of B cells and CD45R+ CD4+ T cells. We did not find clear evidence of a selective retention of CD8+ T cells in the retinas in late disease. Proliferation assays using retinal preparations demonstrated modest but significant responses to both S-Ag and the purified protein derivative of Mycobacterium tuberculosis (PPD) compared with lymph node preparations. The S-Ag response was abrogated by anti-major histocompatibility complex (MHC) class II monoclonal antibody (mAb). Lymphocyte preparations from inflamed retinas have not been examined previously in vitro but are likely to be useful in defining the precise function of CD4+ T cells during the course of EAU.

The differentiation of O-2A progenitor cells into oligodendrocytes is associated with a loss of inducibility of Ia antigens.

Current data suggest that some astrocytes, one of the 3 main types of macroglia in the central nervous system (CNS), can be induced by interferon-gamma (IFN-gamma) to express major histocompatibility complex class II antigens (immune-associated or Ia) and present antigen to T lymphocytes. In contrast, oligodendrocytes, another type of macroglia, cannot be induced to express Ia. The astrocytes which have been shown to express Ia are from a particular glial lineage and are called type-1 astrocytes. The oligodendrocyte-type-2 astrocyte (O-2A) lineage, which gives rise to oligodendrocytes, also gives rise to a second class of astrocytes called type-2 astrocytes and the ability of type-2 astrocytes or the common O-2A progenitor cell to express Ia is not known. We have now found that both type-2 astrocytes and O-2A progenitor cells can be induced to express Ia by IFN-gamma but Ia expression is not induced in oligodendrocytes in parallel cultures. Thus, it appears that differentiation of O-2A progenitor cells into oligodendrocytes is specifically associated with a loss of inducibility of Ia. This apparent loss of the capacity for Ia expression, and presumably antigen presentation, in oligodendrocytes (the cells which produce myelin in the CNS) is of particular interest in view of the ability of immunization of myelin components to produce autoimmune-mediated paralytic disease.

Lymphocyte adhesion and transendothelial migration in the central nervous system: the role of LFA-1, ICAM-1, VLA-4 and VCAM-1. off.

Lymphocyte adhesion to and migration across endothelial cell (EC) monolayers, derived from the rat blood-retinal barrier (BRB), were measured in vitro. The binding of concanavalin A (Con A)-activated peripheral lymph node lymphocytes and the migration of CD4+ T-cell lines could be significantly increased by treating the EC with interleukin-1 beta (IL-1 beta). To determine the role of various adhesion molecules during the processes of lymphocyte binding and transmonolayer migration (diapedesis), lymphocytes were treated with monoclonal antibody (mAb) specific for CD11a (alpha L subunit of leucocyte functional antigen-1; LFA-1), CD18 (beta 2 subunit of leucam family) and CD49d (alpha 4 subunit of very late activation antigen-4; VLA-4) and EC with mAb specific for CD54 (intercellular adhesion molecule-1; ICAM-1) and CD106 (vascular cell adhesion molecule-1; VCAM-1). Binding of the highly adhesive but non-migratory Con A-activated lymphocytes was inhibited by mAb to CD11a (reduced to 73% and 65% of control lymphocyte adhesion) and CD18 (42% and 54%) on non-activated and IL-1 beta-treated EC, respectively, but not by mAb to ICAM-1 or VCAM-1. Diapedesis of the highly migratory T-cell line lymphocytes was also blocked by antibodies to CD11a (reduced to 11% and 10% of control T-cell migration), CD18 (29% and 43%) but in addition was also inhibited by anti-ICAM-1 (17% and 53%) on non-activated and IL-1 beta treated EC, respectively. Both anti-VLA-4 and anti-VCAM-1 were also effective in producing a smaller reduction in migration, but only on IL-1 beta activated EC (66% and 58% of control migration, respectively). These studies indicate that lymphocyte adhesion to central nervous system (CNS) vascular EC is largely dependent on LFA-1 but not through its interaction with ICAM-1. In contrast, lymphocyte diapedesis is mostly supported through the LFA-1/ICAM-1 pairing, with a small proportion being mediated by VLA-4/VCAM-1 on IL-1 beta-activated EC. This latter pathway, however, also appears to be dependent on LFA-1 interacting with the EC.

Identification and characterization of cells infiltrating the graft and aqueous humour in rat corneal allograft rejection.

In a rat model of corneal transplantation, Fischer 344 (RT1(lv1)) rats received orthotopic corneal isografts or Wistar-Furth (RT1(u)) donor allografts. Rejection was observed in 25 of 26 allograft recipients, at a median time of 18 days, with all isografts surviving > 100 days. Flow cytometric analysis of aqueous humour identified cellular infiltration of the aqueous at the time of allograft rejection, in contrast to the acellular aqueous found in isografts at corresponding times following transplantation. A higher proportion of CD8+ than CD4+ cells was found at days 1-3 following rejection, whereas there was a higher proportion of CD4+ cells at days 5-8. No changes in peripheral blood T cell subsets were found at the time of rejection. Immunohistochemical analysis of cells infiltrating recipient iris and grafted cornea undertaken at days 1-2, 4 and 7-10 following onset of rejection, demonstrated inflammatory cells in the graft epithelium, stroma and aggregated on the endothelium. Large numbers of macrophages, T cells (CD4+ > CD8+ at all time points), natural killer (NK) cells and neutrophils were detected in graft tissue at days 1-2 and 4, diminishing after that time. Most infiltrating cells expressed MHC class II antigen, and a smaller number expressed IL-2R. Expression of the co-stimulatory marker B7 was identified in a few cells at day 4 in the region of the graft-host wound. The immune response in graft rejection was characterized at day 4 also by expression of intercellular adhesion molecule-1 (ICAM-1) on endothelial cells of iris and corneal vessels, demonstration of interferon-gamma on mononuclear cells in the peripheral (recipient) cornea, and tumour necrosis factor-alpha on aggregated mononuclear cells on the graft, but not recipient, endothelium. Only sparse cellular infiltrates were found in isograft controls, with inflammation located at the graft-host wound. These findings suggest that inflammatory cells reach a corneal allograft by two routes--from vessels in the peripheral recipient cornea, and from vessels in the recipient iris via the aqueous humour. Different aqueous and intragraft T cell subset proportions were seen early in rejection, although a preponderance of CD4+ cells was found in both aqueous and graft at later times.

Nucleotide sequence of the coat protein gene of pea seed-borne mosaic potyvirus.

The nucleotide sequence of a 1355 bp cDNA representing the 3'-terminal sequences of pea seed-borne mosaic virus (PSbMV) was determined. This sequence contained a single long open reading frame (ORF) of 1189 bp ending with a single TAA termination codon. Downstream from the ORF was an untranslatable region of 189 bp followed by eight bp of polyadenylate. The probable location of the PSbMV coat protein codons within the long ORF was determined by comparing the inferred amino acid sequence with other potyviral coat protein sequences and by examining the sequence for a potyviral polyprotein cleavage cassette sequence. Direct chemical sequencing of the PSbMV coat protein revealed it to be blocked at its amino terminus. A partial amino acid sequence representing the N terminus of the protease-resistant core of the coat protein was determined, however. Alignment of the PSbMV coat protein sequence and the sequences of seven other potyviral coat proteins revealed significant homology, ranging from 53.7% for potato virus Y strain D to 43.2% for tobacco vein mottling virus.