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J D Isaacs

Publications and source records attributed to J D Isaacs.

At least 19 recordsLinked to original sources
PubMed2006

Early rheumatoid arthritis is associated with a deficit in the CD4+CD25high regulatory T cell population in peripheral blood.

OBJECTIVE: Our aim was to test the hypothesis that there is a deficit in the CD4+CD25high regulatory T-cell population in early rheumatoid arthritis (RA), either in size or functional activity. METHODS: Peripheral blood mononuclear cells were examined from subjects with early active RA who had received no previous disease-modifying therapy (n = 43), from individuals with self-limiting reactive arthritis (n = 14), from subjects with stable, well-controlled RA (n = 82) and from healthy controls (n = 72). The frequencies of CD4+CD25high T-cells were quantified using flow cytometry, and function was assessed by the ability to suppress proliferation of CD4+CD25- T-cells. Paired blood and synovial fluid was analysed from a small number of RA and reactive arthritis patients. RESULTS: There was a smaller proportion of CD4+CD25high T-cells in the peripheral blood of early active RA patients (mean 4.25%) than in patients with reactive arthritis or in controls (mean 5.90 and 5.30%, respectively, P = 0.001 in each case). Frequencies in stable, well-controlled RA (mean 4.63%) were not significantly different from early active RA or controls. There were no differences in suppressor function between groups. Higher frequencies of CD4+CD25high T-cells were found in synovial fluid than blood in both RA and reactive arthritis. CONCLUSIONS: These data demonstrate a smaller CD4+CD25high regulatory T-cell population in peripheral blood of individuals with early active RA prior to disease-modifying treatment. This may be a contributory factor in the susceptibility to RA and suggests novel approaches to therapy.

Adult↗
PubMed2006

The role of the cellular prion protein in the immune system.

Prion protein (PrP) plays a key role in the pathogenesis of prion diseases. However, the normal function of the protein remains unclear. The cellular isoform (PrP(C)) is expressed widely in the immune system, in haematopoietic stem cells and mature lymphoid and myeloid compartments in addition to cells of the central nervous system. It is up-regulated in T cell activation and may be expressed at higher levels by specialized classes of lymphocyte. Furthermore, antibody cross-linking of surface PrP modulates T cell activation and leads to rearrangements of lipid raft constituents and increased phosphorylation of signalling proteins. These findings appear to indicate an important but, as yet, ill-defined role in T cell function. Although PrP(-/-) mice have been reported to have only minor alterations in immune function, recent work has suggested that PrP is required for self-renewal of haematopoietic stem cells. Here, we consider the evidence for a distinctive role for PrP(C) in the immune system and what the effects of anti-prion therapeutics may be on immune function.

Animals↗
PubMed2005

Outcome of intensive immunosuppression and autologous stem cell transplantation in patients with severe rheumatoid arthritis is associated with the composition of synovial T cell infiltration.

OBJECTIVE: To determine clinical and immunological correlates of high dose chemotherapy (HDC) + autologous stem cell transplantation (ASCT) in patients with severe rheumatoid arthritis (RA), refractory to conventional treatment. METHODS: Serial samples of peripheral blood and synovial tissue were obtained from seven patients with RA treated with HDC and autologous peripheral blood grafts enriched for CD34+ cells. Disease activity was assessed with the Disease Activity Score (DAS), serum concentrations of C reactive protein (CRP), and human immunoglobulin (HIg) scans, and the extent of immunoablation was determined by immunophenotyping of peripheral blood mononuclear cells, and immunohistochemistry and double immunofluorescence of synovium. RESULTS: Clinical responders (n = 5) had a larger number of cells at baseline expressing CD3, CD4, CD27, CD45RA, CD45RB, and CD45RO in synovium (p < 0.05), higher activity on HIg scans (p = 0.08), and a trend towards higher concentrations of CRP in serum than non-responders (n = 2). Subsequent remissions and relapses in responders paralleled reduction and re-expression, respectively, of T cell markers. A relatively increased expression of CD45RB and CD45RO on synovial CD3+ T cells was seen after HDC + ASCT. No correlations were found between DAS and changes in B cells or macrophage infiltration or synoviocytes. CONCLUSIONS: HDC + ASCT results in profound but incomplete immunoablation of both the memory and naïve T cell compartment, which is associated with longlasting clinical responses in most patients. The findings provide strong circumstantial evidence for a role of T cells in established RA, and demonstrate a role for the synovium in post-transplantation T cell reconstitution.

Adult↗
PubMed2005

Analysis of the insertion/deletion related polymorphism within T cell antigen receptor beta variable genes in primary Sjögren's syndrome.

OBJECTIVE: To analyse T cell receptor beta variable (TCRBV) gene polymorphisms (insertion/deletion related polymorphism (IDRP) and BV6S7) in primary Sjögren's syndrome (PSS). METHODS: Genomic DNA was extracted from blood samples from patients fulfilling the modified European criteria for PSS (n = 61). Healthy control blood samples were obtained from the Blood Transfusion Service (n = 121). As a disease control group, samples from patients with systemic lupus erythematosus (n = 42) were analysed. BV6S7 was genotyped using an established PCR/RFLP method. The IDRP was determined by comparison of the intensity of PCR product bands from within BV9S2 and an internal control region (BV9S1), to ascertain whether 0, 1, or 2 copies of the insertion were present. RESULTS: There was a decrease (p = 0.018) in the proportion of PSS patients with the deleted/deleted genotype. There was no association with specific BV6S7 alleles or genotypes with either the PSS group or the hypergammaglobulinaemic subgroup. There were no significant differences in haplotype frequencies after Bonferroni correction. CONCLUSIONS: A reduced proportion of patients with PSS have the deleted/deleted genotype. Eighty nine per cent of PSS patients have at least one extra germline copy of BV13S2*1. This may relate to previous observations of increased BV13 specific T cells and mRNA in the salivary glands.

Gene Deletion↗
PubMed2003

Prospective study of anti-tumour necrosis factor receptor superfamily 1B fusion protein, and case study of anti-tumour necrosis factor receptor superfamily 1A fusion protein, in tumour necrosis factor receptor associated periodic syndrome (TRAPS): clinical and laboratory findings in a series of seven patients.

OBJECTIVE: To assess the effects prospectively of tumour necrosis factor (TNF) receptor superfamily (TNFRSF) fusion proteins TNFRSF1B (etanercept) and TNFRSF1A (p55TNFr-Ig) in patients with TNF receptor associated periodic syndrome (TRAPS). METHODS: Seven patients with a clinical and genetic diagnosis of TRAPS received subcutaneous etanercept for 24 weeks. One of these patients had previously received an intravenous infusion of p55TNFr-Ig. Therapeutic response was assessed by comparing corticosteroid requirement, acute-phase response and an established scoring system over 20 weeks, both on and off etanercept. RESULTS: Etanercept was well tolerated. The five corticosteroid-responsive patients required significantly less corticosteroids and demonstrated reductions in acute-phase reactants on etanercept. The two patients not requiring corticosteroids had small reductions in disease activity scores. The effect of p55TNFr-Ig in a single patient with TRAPS remains unclear. CONCLUSIONS: Etanercept does not abolish inflammatory attacks but improves disease activity allowing corticosteroid reduction. Etanercept may be clinically useful in replacing or reducing steroid requirements in the treatment of TRAPS. A formal trial of etanercept to establish its role in clinical management is indicated.

Adult↗
PubMed2003

FcgammaRIIIA-158V and rheumatoid arthritis: a confirmation study.

OBJECTIVES: To develop a robust assay for genotyping the FcgammaRIIIA-158V/F polymorphism and to confirm the putative association between the FcgammaRIIIA-158V allele and rheumatoid arthritis (RA). METHODS: This allelic association study examined the FcgammaRIIIA-158V/F polymorphism for association with RA. A novel single-stranded conformational polymorphism assay was used to genotype 828 RA patients and 581 controls from the UK. RESULTS: The FcgammaRIIIA-158V allele was associated with both RA (P=0.02) and nodules (P=0.04). Individuals homozygous for this higher affinity allele had a significantly increased risk of RA (OR 1.53, 95% CI 1.08-2.18) and the development of nodules (OR 2.20, 95% CI 1.20-4.01). There was no evidence of an interaction with the shared epitope. CONCLUSIONS: We have developed a novel assay to genotype the FcgammaRIIIA-158F/V polymorphism and confirmed that homozygosity for the FcgammaRIIIA-158V allele is associated with UK Caucasian RA, particularly in those individuals with nodules, suggesting FcgammaRIIIA may play a role in determining disease severity or in the development of nodules per se.

Adolescent↗
PubMed2003

Overexpression of transcripts containing LINE-1 in the synovia of patients with rheumatoid arthritis.

OBJECTIVE: To identify novel diagnostic markers by comparing gene expression in rheumatoid (RA) and reactive arthritis (ReA) synovium. METHODS: Synovial biopsy specimens were obtained by needle arthroscopy from the knees of 10 patients with either RA or ReA. RNA was isolated from the biopsy specimens and cDNA synthesised for analysis using a customised cDNA macroarray. Confirmatory analysis was performed using in situ hybridisation on a second set of synovial samples. RESULTS: Two unique transcripts (ReXS1 and fibronectin) were consistently more abundant in ReA and three homologous transcripts were more abundant in RA. The latter all mapped within long interspersed nucleotide elements (LINE-1), that form one of the families of repetitive sequences in the human genome. CONCLUSIONS: The abundance of transcripts containing LINE-1 in the RA synovium may be an epiphenomenon or may have pathogenic significance. Further work is required to determine the identity of the full length transcript(s) before its use as a diagnostic marker in RA can be assessed.

Adolescent↗
PubMed2001

Human CD4(+)CD25(+) cells: a naturally occurring population of regulatory T cells.

Despite thymic deletion of cells with specificity for self-antigens, autoreactive T cells are readily detectable in the normal T-cell repertoire. In recent years, a population of CD4(+) T cells that constitutively express the interleukin-2 receptor-alpha chain, CD25, has been shown to play a pivotal role in the maintenance of self-tolerance in rodent models. This study investigated whether such a regulatory population exists in humans. A population of CD4(+)CD25(+) T cells, taken from the peripheral blood of healthy individuals and phenotypically distinct from recently activated CD4(+) T cells, was characterized. These cells were hyporesponsive to conventional T-cell stimuli and capable of suppressing the responses of CD4(+)CD25(-) T cells in vitro. Addition of exogenous interleukin-2 abrogated the hyporesponsiveness and suppressive effects of CD4(+)CD25(+) cells. Suppression required cell-to-cell contact but did not appear to be via the inhibition of antigen-presenting cells. In addition, there were marked changes in the expression of Notch pathway molecules and their downstream signaling products at the transcriptional level, specifically in CD4(+)CD25(+) cells, suggesting that this family of molecules plays a role in the regulatory function of CD4(+)CD25(+) cells. Cells with similar phenotype and function were detected in umbilical venous blood from healthy newborn infants. These results suggest that CD4(+)CD25(+) cells represent a population of regulatory T cells that arise during fetal life. Comparison with rodent CD4(+)CD25(+) cells suggests that this population may play a key role in the prevention of autoimmune diseases in humans.

Adult↗
PubMed2001

Morbidity and mortality in rheumatoid arthritis patients with prolonged and profound therapy-induced lymphopenia.

OBJECTIVE: Therapies that deplete lymphocytes often improve symptoms in patients with otherwise refractory autoimmune disease but may result in long-term lymphopenia, the consequences of which are uncertain. To assess the impact of prolonged lymphopenia on morbidity and mortality, we studied patients who had previously received lymphocytotoxic monoclonal antibody (mAb) therapy for rheumatoid arthritis (RA). METHODS: Fifty-three patients who received the lymphocytotoxic mAb CAMPATH-1H between 1991 and 1994 in the United Kingdom were assessed for mortality and infectious and malignant morbidity, by interview and case-note review. In addition, patients were monitored via the National Health Service Central Registry, to verify notification of death. Peripheral blood lymphocyte subsets were analyzed by flow cytometry. A retrospective, matched-cohort study of mortality was also performed with 102 control subjects selected from the European League Against Rheumatism database, which comprises patients with rheumatic disorders who have received immunosuppressive drugs. RESULTS: There was profound and persistent peripheral blood lymphopenia in the mAb-treated patients, affecting predominantly the CD4+ subset. Median CD4+, CD8+, and CD19+ peripheral blood lymphocyte counts at 73-84 months after therapy were 185 cells/microl, 95 cells/microl, and 115 cells/microl, respectively. At a median followup of 71 months (range 14-90), 13 patients had died (24.5%), compared with 18% of the matched controls, providing a mortality rate ratio of 1.45 (95% confidence interval 0.65-3.13). During 283 patient-years of followup, there were 36 infections classified as major (12.7 per 100 patient-years). The causes of death and the spectrum of infections documented were similar to those expected in a hospital-based RA cohort. Patients who received more than 1 course of therapy had more severe lymphopenia than did patients who received a single course, but this did not have an impact on mortality or morbidity. CONCLUSION: Despite the occurrence of profound and long-lasting lymphopenia following treatment with antilymphocyte mAb therapy for RA, this therapy is not associated with a large excess of mortality nor with an unusual spectrum of infections, at least during a medium-term period of followup. These data are also relevant to patients receiving lymphocytotoxic mAb therapy for other indications, and to patients receiving other lymphodepleting therapies such as autologous stem cell transplantation.

Aged↗
PubMed2001

Application of differential display to immunological research.

The majority of immunological processes are mediated by cell-to-cell contact or receptor-ligand interactions that transmit intracellular signals and affect the regulation of transcription in the nucleus. As a consequence, precursor cells develop into their respective lineages and cells differentiate further during an immune response. In order to study changes in normal cells or even cells that have been isolated from diseased tissue, a number of approaches have been developed. One such method, differential display (DDRT-PCR), is a versatile technique for the analysis of gene expression that is based on RT-PCR and denaturing polyacrylamide gel electrophoresis. This technique is applicable to multiple samples of clonal or purified cell populations as well as to complex tissues and can be used to provide mRNA fingerprints. However, the main purpose of DDRT-PCR is to isolate differentially regulated genes in biological systems. The method is carried out without prior hypothesis as to which genes should be examined and so increases the possibility of identifying completely novel and unexpected changes in transcription. A major drawback has been the isolation of false positive clones and the need to confirm the results of analysis by another method. This makes DDRT-PCR labour intensive. A number of strategies have been recommended to reduce these problems, including reverse-northern analysis as a confirmatory step for screening putative differentials. In order to reduce the number of gel fingerprints that would be required to cover all the mRNAs in a cell, several focused approaches have been suggested. These include targeted differential display for the isolation of multigene families that have conserved protein domains or gene signatures and subtractive differential display whereby one population is subtracted from the other prior to screening. The purpose of this review is to provide some guidance to the immunologist who might wish to apply DDRT-PCR in their research. A number of examples where DDRT-PCR has been used successfully in immunological research are included.

Animals↗
PubMed2001

Does the shared epitope genotype influence either the susceptibility to or the phenotype of corneal melting?

PURPOSE: To investigate the role of the shared epitope alleles in determining susceptibility to and the phenotype of corneal melting in patients with rheumatoid arthritis (RA). METHODS: The HLA class 1 and 2 genotype was determined for 17 patients with rheumatoid-associated comeal melting by the phototyping method. HLA-DR4 subtyping was performed by PCR sequence-based typing. The frequency of all the shared epitope alleles and, in particular, of the higher-risk *0401 and *0404 alleles, was compared with healthy controls and unrelated RA patients, with and without extra-articular manifestations. A comparison was also made between the shared epitope genotype of the corneal melt patients and local, ocular disease characteristics. RESULTS: Thirteen (76%) patients with corneal melt possessed at least one shared epitope allele and 5 (29%) possessed two alleles. The dominant alleles were variants of the DR4 family, notably the *0401, *0404 and *0408 alleles. Both the allele frequency and a double dose of shared epitope alleles were more common in the three RA patient groups than in the healthy, control group (p < 0.005). Although the frequency of the higher-risk alleles was similar in the three RA patient group, a trend existed for a double dose of higher-risk alleles to be more common in the patients with either corneal melt or other extra-articular manifestations (p > 0.2). No association was found between the number or type of shared epitope alleles and any of the ocular disease characteristics studied. CONCLUSIONS: The results of this study suggest that the shared epitope alleles do not influence the ocular disease phenotype of corneal melt in RA patients. Shared epitope determination of RA patients may help to identify those susceptible to either corneal melt or other extra-articular disease. RA patients with a double dose of higher-risk alleles may have an increased risk of corneal melt.

Alleles↗
PubMed2001

From bench to bedside: discovering rules for antibody design, and improving serotherapy with monoclonal antibodies.

Anti-T-cell monoclonal antibodies (mAbs) form a unique class of therapeutic agent. Their precise specificity offers tremendous potential for the treatment of autoimmune and inflammatory diseases but also prevents meaningful preclinical animal studies. In particular, adverse reactions to therapy may be unanticipated, and the first administration of a novel T-cell mAb to a patient thus marks the beginning of a unique experiment. By comparing clinical parameters and laboratory measurements, small-scale pilot studies can provide detailed information about mAb biology that both predicts and suggests solutions to the complications of therapy. In this essay I illustrate this concept with reference to three specific areas: lymphocyte depletion, mAb immunogenicity and cytokine-release syndromes. In each case, systematic clinical and laboratory science has improved our understanding of the problem and suggested solutions; most of these solutions have been or are being adopted. Thus, small, open studies are an essential step in the development of novel mAbs, provide an ideal platform for the study of mAb biology, and serve as an early warning system for potential adverse effects.

Animals↗
PubMed2001

Detection of Mycobacterium tuberculosis group organisms in human and mouse joint tissue by reverse transcriptase PCR: prevalence in diseased synovial tissue suggests lack of specific association with rheumatoid arthritis.

Infection with mycobacterial species, including Mycobacterium tuberculosis, has long been implicated in the etiopathology of rheumatoid arthritis (RA) on the basis of clinical and pathological similarities between tuberculosis and RA. Despite evidence of immune responses to mycobacterial antigens in RA patient synovial fluid, cross-reactivity between these and host joint antigens, and the presence of M. tuberculosis protein antigen in RA synovial fluid, a definite causal association with RA has not been shown. Previous studies from our laboratory using reverse transcriptase PCR (RT-PCR) of bacterial rRNAs have shown RA synovium to be colonized by a diverse range of bacteria, most of commensal origin. However, M. tuberculosis group organism (MTG) RNA sequences were found in one RA patient tissue. Since this was considered of sufficient interest to warrant further investigation, we devised a M. tuberculosis-specific nested RT-PCR test which could be used for detection of MTG in a mixed pool of bacterial crDNAs. This test was used to investigate the distribution of MTG in RA synovial tissue and also non-RA arthritis and healthy control tissues and was also used to examine the tissue distribution of MTG in an acute and chronic model of M. tuberculosis infection in the BALB/c mouse. MTG sequences were found in a high proportion of RA patient synovial tissues but also in non-RA arthritis control tissues at lower frequency. This likely reflects trafficking of persistent M. bovis BCG to inflamed joint tissue, irrespective of cause. MTG were not found in healthy synovial tissue or the tissue of patients with undifferentiated arthritis. In both the acute and chronic models of infection in BALB/c mice, M. tuberculosis was also found to have trafficked to joint tissues, however, no signs of inflammation, arthritis, or pathology associated with M. tuberculosis infection was seen. These combined results would argue against a specific causal role of MTG in RA-like arthritis; however, their role as adjuvant in immune dysfunction in an innately susceptible host cannot be excluded.

Acute Disease↗
PubMed2001

Rheumatoid arthritis synovial T cells regulate transcription of several genes associated with antigen-induced anergy.

Rheumatoid arthritis (RA) is a chronic, inflammatory synovitis whose pathogenesis may involve autoimmune mechanisms. Anergy is a state of T-cell nonresponsiveness characterized by downregulated IL-2 production. Paradoxically, RA T cells are hyporesponsive and proliferate poorly to antigens and mitogens, thus sharing some characteristics with anergic T cells. We analyzed the molecular basis of anergy in cloned human CD4+ T cells using differential display RT-PCR and subsequently examined the levels of differentially expressed transcripts in RA and, as control, reactive arthritis (ReA) synovium. Several transcriptional events were common to anergic T cells and RA synovium. These included downregulation of CALMODULIN:, which is critical to T-cell activation, and of cellular apoptosis susceptibility protein, which may mediate resistance to apoptosis in RA. Transcription of CALMODULIN: in RA synovium was less than 1% of that in ReA and was lower in RA synovial fluid mononuclear cells than in paired PBMCs. Following anti-TNF-alpha therapy in vivo, RA PBMC CALMODULIN: transcripts increased five- to tenfold. Pharmacological calmodulin blockade in vitro impaired antigen-specific proliferation. These data provide a link between reduced CALMODULIN: transcription and impaired T-cell responsiveness in RA. The identification of transcriptional changes common to anergic and RA synovial T cells should help interpret some of the characteristic RA cellular defects.

Antigens↗
PubMed2000

Fcgamma receptor type IIIA is associated with rheumatoid arthritis in two distinct ethnic groups.

OBJECTIVE: To investigate a possible association between a functional polymorphism in the intermediate-affinity receptor for IgG called Fc-gamma receptor type IIIA (FcgammaRIIIA [CD16]) and rheumatoid arthritis (RA). METHODS: This was an allelic association study in which a single nucleotide polymorphism in FcgammaRIIIA was examined as a susceptibility and/or severity factor for RA. The FcgammaRIIIA-158V/F polymorphism was genotyped by direct sequencing in 2 well-characterized ethnic groups, UK Caucasians (141 RA patients and 124 controls) and North Indians and Pakistanis (108 RA patients and 113 controls). RESULTS: The FcgammaRIIIA-158V/F polymorphism was associated with RA in both ethnic groups (P = 0.028 for UK Caucasians, P = 0.050 for North Indians and Pakistanis, and P = 0.003 for both groups combined). FcgammaRIIIA-158VF and -158W individuals had an increased risk of developing RA in both populations (UK Caucasians odds ratio [OR] 1.6, P = 0.050; North Indians and Pakistanis OR 1.9, P = 0.023; and combined groups OR 1.7, P = 0.003). In the UK Caucasian group, the highest risk was for nodular RA, a more severe disease subset, associated with homozygosity for the FcgammaRIIIA-158V allele (OR 4.4, P = 0.004). There was also evidence for an interaction between the RA-associated HLA-DRB1 allele and the presence of at least 1 FcgammaRIIIA-158V allele in predicting susceptibility to RA (OR 5.5, P = 0.000). CONCLUSION: We have demonstrated that the FcgammaRIIIA-158V/F polymorphism is a susceptibility and/or severity marker for RA in 2 distinct ethnic groups. This finding may ultimately provide additional insights into the pathogenesis of RA and other autoantibody/immune complex-driven autoimmune diseases.

Alleles↗
PubMed2000

The value of sonography in the detection of bone erosions in patients with rheumatoid arthritis: a comparison with conventional radiography.

OBJECTIVE: The ability to make an early, accurate diagnosis of rheumatoid arthritis (RA) has become increasingly important with the availability of new, expensive, and targeted therapies. However, plain radiography, the traditional method of detecting the characteristic bone erosions and an important adjunct in establishing a diagnosis of RA, is known to be insensitive. This study compared sonography, a modern imaging technique, with conventional radiography for the detection of erosions in the metacarpophalangeal (MCP) joints of patients with RA. METHODS: One hundred RA patients (including 40 with early disease) underwent posteroanterior radiography and sonography of the MCP joints of the dominant hand. Twenty asymptomatic control subjects also underwent sonography. Erosion sites were recorded and subsequently compared using each modality. Magnetic resonance imaging (MRI) was performed on the second MCP joint in 25 patients with early RA to confirm the pathologic specificity of sonographic erosions. Intraobserver reliability of sonography readings was assessed using video recordings of 55 MCP joint scans of RA patients, and interobserver reliability was assessed by comparing 160 MCP joint scans performed sequentially by 2 independent observers. RESULTS: Sonography detected 127 definite erosions in 56 of 100 RA patients, compared with radiographic detection of 32 erosions (26 [81%] of which coincided with sonographic erosions) in 17 of 100 patients (P < 0.0001). In early disease, sonography detected 6.5-fold more erosions than did radiography, in 7.5-fold the number of patients. In late disease, these differences were 3.4-fold and 2.7-fold, respectively. On MRI, all sonographic erosions not visible on radiography (n = 12) corresponded by site to MRI abnormalities. The Cohen-kappa values for intra- and interobserver reliability of sonography were 0.75 and 0.76, respectively. CONCLUSION: Sonography is a reliable technique that detects more erosions than radiography, especially in early RA. Sonographic erosions not seen on radiography corresponded to MRI bone abnormalities. This technology has potential in the management of patients with early RA/inflammatory arthritis and is likely to have major implications for the future practice of rheumatology.

Adult↗
PubMed2000

Local bioactive tumour necrosis factor (TNF) in corneal allotransplantation.

The aim of this study was to examine the kinetic profile of bioactive TNF levels in aqueous humour of rabbit eyes undergoing corneal allograft rejection and to investigate the effect of locally blocking TNF activity after corneal transplantation. In a rabbit corneal transplantation, endothelial allograft rejection was identified and correlated with increase in central graft thickness. Samples of aqueous humour obtained on alternate days following transplantation were tested for TNF mRNA and bioactive TNF protein. To investigate the effect of locally blocking TNF activity in allograft recipients, the fusion protein TNFR-Ig was administered by injections into the anterior chamber after transplantation. Pulsatile increases in levels of this cytokine were found in 14 of 15 allograft recipients. Peaks of TNF bioactivity preceded by varying intervals the observed onset of rejection in allograft recipients. TNF levels were not elevated in aqueous humour from corneal autograft recipient controls or in serum of allografted animals. mRNA levels were elevated before onset of and during clinically observed allograft rejection. In three of seven animals receiving TNFR-Ig injections on alternate days from day 8 to day 16 post-transplant, clear prolongation of corneal allograft survival was demonstrated. Bioactive TNF is present in aqueous humour following rabbit corneal allotransplantation. Rather than correlating directly with endothelial rejection onset, pulsatile peak levels of TNF precede and follow the observed onset of endothelial rejection. Blockade of TNF activity prolongs corneal allograft survival in some animals, indicating that this cytokine may be a suitable target in local therapy of corneal allograft rejection.

Animals↗