Cytotoxic T-lymphocyte Antigen 4 CT60 Research Articles

The association of cytotoxic T-lymphocyte antigen-4 + 49A/G and CT60 polymorphisms with type 1 diabetes and latent autoimmune diabetes in Chinese adults.

The aim of this study was to investigate the association of cytotoxic T-lymphocyte antigen-4 (CTLA-4) + 49A/G and CT60 polymorphisms with latent autoimmune diabetes in adults (LADA) and the genetic differences between LADA, type 1 diabetes (T1DM), and type 2 diabetes (T2DM) in a Chinese population. A total of 231 LADA, 402 T1DM, and 330 T2DM patients as well as 482 nondiabetic controls were recruited in the study. CTLA-4 + 49A/G and CT60 polymorphisms were analyzed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). The level of glutamic acid decarboxylase antibodies (GADAs) was detected by a radioligand binding assay. The CTLA-4 + 49A/G risk genotype GG was most frequent in T1DM patients (45.3%), followed by LADA patients (44.2%) and T2DM patients (38.8%). Significantly higher frequencies of the risk genotype GG were observed in the T1DM (OR = 1.532, 95% CI 1.168-2.010, P = 0.002) and LADA patients (OR = 1.464, 95% CI 1.063-2.017, P = 0.019). The frequencies of the CTLA-4 CT60 risk genotype GG were 65.2, 61.9, 58.5, and 56.4% in the T1DM, LADA, T2DM, and control groups, respectively. The CTLA-4 CT60 GG risk genotypes were only associated with T1DM (OR = 1.445, 95% CI 1.1-1.898, P = 0.008). Compared with controls, patients having a high titer of GADA (GADA ≥ 180 IU/ml) had higher frequencies of the GG risk genotype of CTLA-4 + 49 A/G (49.4% vs. 35.1% OR = 1.807, 95% CI 1.125-2.903, P = 0.014), but there was no difference between patients having a low titer of GADA and controls. The CTLA-4 + 49 A/G polymorphism confers genetic susceptibility to LADA and T1DM, while the CTLA-4 CT60 polymorphism is only associated with T1DM in Chinese population. The CTLA-4 + 49 A/G genotype distribution in LADA is associated with the GADA level.

Association between CTLA-4 polymorphisms and susceptibility to Celiac disease: A meta-analysis

The study explored whether cytotoxic T lymphocyte antigen-4 (CTLA-4) polymorphisms confer susceptibility to Celiac disease (CD). A meta-analysis was conducted on the associations between the CTLA-4 CT60 A/G, +49 A/G, -318 C/T polymorphisms and CD using allele contrast, a recessive model, a dominant model, and homozygote contrast. Thirteen separate comparison studies were considered in the meta-analysis consisting of 5072 patients with CD and 13,462 controls. All subjects were Europeans. Meta-analysis of the CTLA-4 CT60 A/G polymorphism showed an association between CD and the CTLA-4 CT60 G allele in all subjects [Odds ratio (OR) = 1.160, 95% Confidence interval (CI) = 1.104-1.219, p < 1.0 × 10(-9)). Meta-analysis using the recessive model also revealed an association between CD and the CTLA-4CT60 GG genotype (OR = 1.331, 95% CI = 1.093-1.620, p = 0.004). Furthermore, analyses using the dominant model and homozygote contrast showed the same pattern as that shown by the CTLA-4CT60 G allele. Meta-analysis of the CTLA-4 +49 A/G polymorphism showed no association between CD and the CTLA-4 +49 G allele in all subjects (OR = 0.992, 95% CI = 0.872-1.129, p = 0.907). Meta-analysis using the recessive, dominant model, and homozygote contrast showed the same pattern as that shown by the CTLA-4 +49 Gallele. Meta-analysis of the CTLA-4 -318 C/T polymorphism showed no association between CD and the CTLA-4 -318 T allele in all subjects (OR = 1.018, 95% CI = 0.813-1.275, p = 0.877). The CTLA-4 CT60 A/G polymorphism was associated with CD susceptibility, but no association was found between CTLA-4 +49 A/G and -318 C/T polymorphisms and CD in Europeans.

Cytotoxic T-lymphocyte antigen 4 (CTLA4) +49AG and CT60 gene polymorphisms in Alopecia Areata: a case–control association study in the Italian population

Alopecia Areata (AA) is an autoimmune disease characterized by well-circumscribed patches of hair loss especially from the scalp. Cytotoxic T-lymphocyte antigen 4 (CTLA4) gene, a negative regulator of T cells, has been associated with predisposition to most autoimmune disorders. We evaluated two CTLA4 functional single-nucleotide polymorphisms (SNPs) for potential association with Alopecia Areata in an Italian population using a case-control approach. We genotyped +49AG (rs231775) and CT60 (rs3087243) variants in 130 AA patients and 189 ethnically matched controls by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. CTLA4 +49AG analysis revealed no statistically significant difference in both the allele and genotype frequencies between patients and controls. As regarding CT60 SNP, we found that AA cases less frequently than healthy subjects carried A/A genotype with a higher prevalence of A/G and G/G genotypes (83.8 and 75.1 %; p = 0.041, OR = 0.58, 95 % CI 0.32-1.03), consistent with a dominant effect of G disease risk allele. In particular, it seemed to exert effects mainly in DQ7-negative patients with a less aggressive form of the disease. Haplotype analysis suggested that the G(+49AG), A(CT60) allelic combination was significantly related to a reduced disease risk (p = 0.014, OR = 0.28, 95 % 0.09-0.82). Altogether, our findings confirm that only CTLA4 CT60 polymorphism seems to be an important genetic determinant of Alopecia Areata development in Italian subjects.

The CTLA-4 +49 A/G, CT60 A/G and PTPN22 1858 C/T polymorphisms and susceptibility to vitiligo: a meta-analysis

The aim of this study was to explore whether cytotoxic T lymphocyte antigen-4 (CTLA-4) +49 A/G, CT60 A/G, and protein tyrosine phosphatase nonreceptor 22 (PTPN22) 1858 C/T polymorphisms confer susceptibility to vitiligo. A meta-analysis was conducted of the associations between the CTLA-4 +49 A/G, CT60 and PTPN22 1858 C/T polymorphisms and vitiligo using; (1) allele contrast, (2) the recessive model, (3) the dominant model, and (4) the additive model. A total of 14 separate comparisons were considered in our meta-analysis consisting of 3,404 patients with vitiligo and 5,069 controls (nine studies with 1,252 cases and 2,152 controls for the CTLA-4 polymorphisms and five studies with 1,800 cases and 3,269 controls for the PTPN22 polymorphism). Meta-analysis showed no association between vitiligo and the CTLA-4 +49 A/G polymorphism in all study subjects (OR of the G allele = 1.186, 95 % CI = 0.893-1.575, p = 0.240) and in European (OR = 1.016, 95 % CI = 0.873-1.182, p = 0.838). However, meta-analysis of the CTLA-4 CT60 A/G polymorphism showed an association between vitiligo and the CTLA-4 CT60 G allele in all study subjects (OR = 1.267, 95 % CI = 1.110-1.447, p = 4.5 × 10(-5)) and in the European group (OR = 1.345, 95 % CI = 1.163-1.556, p = 6.3 × 10(-6)). Analysis using the recessive model and homozygote contrast showed the same pattern for the CTLA-4 CT60 G allele. Meta-analysis of the PTPN22 1858 C/T polymorphism showed an association between the PTPN22 T allele and vitiligo in all subjects (OR = 1.507, 95 % CI = 1.320-1.720, p < 1.0 × 10(-8)) and in European group (OR = 1.530, 95 % CI = 1.339-1.748, p < 1.0 × 10(-8)), but not in Asians (OR = 0.482, 95 % CI = 0.152-1.530, p = 0.216). Analysis using the recessive, dominant model, and homozygote contrast showed the same pattern for the PTPN22 T allele. This meta-analysis demonstrates that the CTLA-4 CT60 A/G polymorphism confers susceptibility to vitiligo in Europeans, but no association was found between the CTLA-4 +49 A/G polymorphism and vitiligo susceptibility. The PTPN22 C1858T polymorphism is associated with vitiligo susceptibility in European population.

CTLA-4 GENE POLYMORPHISM IN RELATION TO THYROID DISORDERS IN PATIENTS WITH CHRONIC HEPATITIS C UNDER INTERFERON ALPHA THERAPY

Thyroid autoimmunity and dysfunction have reported as side effects of interferon-α treatment. The CT60 and exon 1+49 A/G polymorphisms in the Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) gene have linked to susceptibility to autoimmune disease. The aim of this research was to analyze the frequencies of CTLA-4 CT60 and +49 A/G polymorphisms and evaluate both polymorphisms as indicators of thyroid disorder susceptibility in chronic HCV Egyptian patients under interferon therapy. This study was carried out on 114 chronic HCV patients under combined therapy of interferon-α and Ribavirin. From them, 60 chronic HCV patients without thyroid disorder were considered the control group. The other 54 patients were having thyroid disorder either hypothyroidism (N = 35) or Grave’s Disease (GD) (N = 19). For all subjects, the genotypes of CTLA-4 gene CT60 and +49 A/G polymorphisms were studied using RFLP technique. For +49 A/G polymorphism, the genotypes frequencies in controls were: AA (30), AG (31.7) and GG (38.3%). Whereas, in hypothyroidism patients, the AA, AG and GG genotypes frequencies were (20), (57.1%) and (22.9%) respectively, while in grave’s disease, the AA, AG and GG genotypes frequencies were (26.3 (57.9) and (15.8%) respectively. The AG genotype was significantly associated with thyroid disease. As regards CT60 polymorphism, the genotypes frequencies in controls were: CC (38.3), CT (35) and TT (26.7%). Whereas, in hypothyroidism patients, the CC, CT and TT genotypes frequencies were (60), (20) and (20%) respectively, while in grave’s disease, the CC, CT and TT genotypes frequencies were (68.4), (15.8) and (15.8%) respectively. The CC genotype was significantly associated with thyroid disorders. CTLA-4 gene +49A/G and CT60 polymorphisms confer susceptibility to autoimmune thyroid disorder and confirm usefulness of CTLA-4 genotyping in predicting thyroid disorder in chronic HCV patients under interferon therapy.

Donor CTLA-4 Genotype Influences Clinical Outcome after T Cell-Depleted Allogeneic Hematopoietic Stem Cell Transplantation from HLA-Identical Sibling Donors

CTLA-4 (cytotoxic T-lymphocyte antigen-4) plays a pivotal role in inhibiting T cell activation through competitive interaction with B7 molecules and interruption of costimulatory signals mediated by CD28. Polymorphisms on the CTLA-4 gene have been previously associated with autoimmune diseases, predisposition to leukemic relapse, and with graft-versus-host disease (GVHD) or relapse after allogeneic transplant. As CTLA-4 is expressed on T-lymphocytes, the aim of this study was to determine whether the donor CTLA-4 CT60 genotype also influences clinical outcome even after T cell depletion with CD34-positive selection. We studied 136 patient-donor pairs. Overall survival (OS) was worse for those patients who received grafts from a donor with the CT60 AA genotype rather than from a donor with the AG or GG genotype (35.6% vs 49.4%; P = .043). This association was confirmed through multivariate analysis, which identified the donor CT60 genotype as an independent risk factor for OS (P = .008; hazard ratio [HR]: 2.24, 95% confidence interval [CI]: 1.23-4.08). The donor CT60 AA genotype was also associated with lower disease-free survival, this being related to an increased risk of relapse (P = .001; HR: 3.41, 95% CI: 1.67-6.96) and a trend toward higher transplant-related mortality. These associations were stronger when considering only patients in the early stage of disease. Our results suggest that graft-versus-leukemia (GVL) activity after T cell depletion is conditioned by the donor CTLA-4 genotype.

The Genotype of T-Cell Costimulatory Molecule Is Associated with Relapse Incidence In Patients with Acute Myeloid Leukemia After Allogeneic Hematopoietic Cell Transplantation

AbstractAbstract 684 Background:Disease relapse is one of the leading causes of death following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Donor T lymphocytes play a critical role in alloimmune recognition and their ability to detect non-self-antigens can lead to graft-versus-host disease (GVHD) or contribute to relapse prevention through recognition and elimination of minimal residual disease. CD28 is the primary T-cell costimulatory molecule constitutively expressed on the majority of T cells. Upon interaction with its ligands B7, CD28 transduces a signal that enhances the activation and proliferation of T cells. Another member of the CD28 family is inducible co-stimulator (ICOS). Although not constitutively expressed, ICOS is rapidly upregulated on T lymphocytes upon activation. Cytotoxic T-lymphocyte antigen 4 (CTLA-4), a homologous molecule of CD28, is a key factor in regulating and maintaining self-tolerance, providing a negative signal to T cells. Although several single-nucleotide polymorphisms (SNPs) within those costimulatory molecule genes have been identified to be associated with the risk of autoimmune disease, their association with outcome after allo-HSCT has yet to be explored. This present study was designed to investigate the influence of CD28, ICOS and CTLA-4 genes polymorphisms on the outcome of patients with acute myeloid leukemia (AML) after allo-HSCT. Methods:The entire study population consisted of 86 consecutive AML patients and their donors who were transplanted from 2001 to 2009 in our Unit. Genomic DNA was extracted from peripheral blood samples obtained from recipients and donors before transplantation. Five SNPs of CD28 -594(A/G), ICOS -693(G/A) and CTLA-4 -1722(A/G), +49(A/G) and CT60(A/G) were analyzed. Results:(1) The media age of the patients was 27 years (range, 12–49 years). At the time of transplantation, 70 patients were in first complete remission (CR), 10 patients in second CR, 3 patients in third CR and 3 patients in progressive status. 33 patients underwent HLA-matched sibling HSCT and 53 patients underwent unrelated HSCT. All patients received myeloablative conditioning based on busulfan/cyclophosphamide (BuCy) without total body irradiation (TBI). The GVHD prophylaxis is consisted of cyclosporin A, a short-term methotrexate and mycophenolate mofetil. (2) Only one patient experienced engraftment failure. 18(20.9%), 20(23.3%) and 3(3.5%) patients respectively developed grade I, II and severe acute GVHD (aGVHD). 16(18.6%) and 15(17.4%) patients developed limited and extensive chronic GVHD (cGVHD). (3) 17 patients (19.8%) experienced relapse, the media time was 15.6 months after allo-HSCT (range, 2–24 months). (4) Patients receiving stem cells from a donor with AA genotype in position +49 or CT60 of CTLA-4 gene relapsed more frequently than those with AG/GG genotypes (for +49: 50% vs 14.1%, P=0.012; for CT60: 80% vs 16%, P<0.0001). (5) Patients receiving stem cells from a donor with CD28 -594 AA genotype had a lower incidence of relapse than those with other genotypes (0 vs 25%, P=0.04), due to a higher incidence of aGVHD (83.3% vs 38.2%, P=0.004). (6) In multivariate analysis, donor with CTLA-4 CT60 AA genotype (RR=13.411, 95%CI: 3.808–47.233, P<0.0001), and absence of cGVHD (RR=2.12, 95%CI: 1.112–4.042, P=0.022) were found to significantly contribute to the risk of relapse after allo-HSCT. Furthermore, patients receiving CTLA-4 CT60 AA genotype donor had worse overall survival at 7 years (20% vs 77.8%, RR=10, 95%CI: 3.761–16.239, P<0.0001). The polymorphic sites CTLA-4 -1722 and ICOS -693 did not correlate with the risk of relapse. Nor did patient 5 polymorphic sites genotype. Conclusions:These results, which is the first report of T-cell costimulatory molecule genes polymorphic features with the risk of leukemia relapse in AML patients after allo-HSCT, suggest an interaction between donor CTLA-4 CT60 AA genotype and the risk of relapse. The CTLA-4 CT60 AA genotype has been reported to increase the production of soluble form of CTLA-4, suggesting that increased expression of CTLA-4 would be associated with a decrease ability of the immune system to detect and eliminate tumor associated antigens. According to our results, anti-CTLA-4 antibodies may be a promising therapeutic strategy in leukemia relapse after allo-HSCT at least in patients receiving CTLA-4 CT60 AA genotype donor. Disclosures:No relevant conflicts of interest to declare.

CTLA4CT60 Single-Nucleotide Polymorphism Is Associated with Slovenian Inflammatory Bowel Disease Patients and Regulates Expression ofCTLA4Isoforms

We have evaluated functional polymorphism (rs3087243; in literature known also as CTLA4 CT60) in the cytotoxic T lymphocyte antigen 4 (CTLA4) gene, previously associated with several autoimmune diseases, for potential association with inflammatory bowel diseases (IBD). In addition, we investigated correlations between CTLA4 CT60 polymorphism and CTLA4 gene expression in peripheral blood lymphocytes and colon biopsies from IBD patients. We genotyped CTLA4 CT60 polymorphism in 266 healthy control subjects and 481 IBD patients and found statistically lower frequency of CTLA4 CT60 AA genotype in IBD patients (13.72%) compared to control subjects (23.31%; p&#x2009;=&#x2009;0.001, odds ratio [OR]&#x2009;=&#x2009;0.504) as well as lower allele frequency of minor A allele in IBD patients (0.346) compared to control subjects (0.461, p&#x2009;&lt;&#x2009;0.001, OR&#x2009;=&#x2009;0.623). The association was confirmed with both major forms of IBD, Crohn's disease, and ulcerative colitis (UC), but was slightly stronger in UC patients, particularly when we compared allele frequency of A allele in UC patients (0.299) and control subjects (0.461, p&#x2009;&lt;&#x2009;0.001, OR&#x2009;=&#x2009;0.500). We found lower expression of the CTLA4 gene in blood lymphocytes from IBD patients compared to control subjects (p&#x2009;&lt;&#x2009;0.001) and higher CTLA4 expression in biopsies taken from inflamed part of the colon compared to noninflamed part of the colon (p&#x2009;=&#x2009;0.021). We found lower expression of soluble CTLA4 isoform than membrane-bound full-length isoform in peripheral blood lymphocytes from IBD patients compared to control subjects (p&#x2009;=&#x2009;0.010) and in lymphocytes from IBD patients with CTLA4 CT60 GG genotype compared to IBD patients with AA genotype (p&#x2009;=&#x2009;0.034). Our genotype and gene expression data suggest that CTLA4 plays a role in IBD pathogenesis. Polymorphism CTLA4 CT60 contributes to genetic susceptibility to IBD in Slovenian population and regulates expression of CTLA4 isoforms.

The CTLA4 variants may interact with the IL23R- and NOD2-conferred risk in development of Crohn's disease

BackgroundThe CTLA4 (cytotoxic T-lymphocyte antigen 4) gene is associated with several immunopathologic diseases and because of its important immuno-regulatory role it may be considered also a plausible candidate for a genetic association with inflammatory bowel diseases. Previously published studies found no association of CTLA4 with Crohn's disease itself, but some indicated an association with its subphenotypes. The aim of this study was to assess the association in the Czech population, using a set of markers shown to associate with other diseases.MethodsSix polymorphisms within the CTLA4 region were investigated in 333 patients with Crohn's disease and 482 unrelated healthy controls, all Caucasians of Czech origin. The genotypes of the SNPs were determined using the TaqMan SNP genotyping assays. Haplotypes were reconstructed using an expectation-maximization algorithm, and their association with the condition was assessed using log-linear modeling. Then, potential interactions were tested between the CTLA4 variants and other genetic factors known to confer the disease susceptibility.ResultsNo crude associations with Crohn's disease were found for the tested CTLA4 variants under the log-additive or dominant models. However, when stratified for the genetic risk conferred by the variants in the NOD2 (the p.Leu1007fsX1008, rs5743293) or the IL23R (p.R381Q, rs11209026), a significant negative association emerged for the minor alleles of CTLA4 CT60 (rs3087243), JO31 (rs11571302), JO27-1 (rs11571297) polymorphisms. This negative association with CTLA4 was apparent only in the strata defined by presence minor alleles at the NOD2 rs5743293 (here the CTLA4 CT60 A coffered an OR = 0.43, 95%CI 0.19 - 0.95 for the presence of CT60 A), or IL23R rs11209026 (here the OR for presence of CT60 A was 0.23, 95%CI 0.07 - 0.71). We observed this effect also for the haplotype consisting of minor alleles of the three tightly linked CTLA4 markers. Furthermore, this haplotype was associated with the younger age at diagnosis (OR 1.52, 95%CI 1.09 - 2.11, p = 0.014).ConclusionsA protective effect of a CTLA4 haplotype was unmasked after stratification for the risk variants in the NOD2 and IL23R genes, and may point towards the biological relevance of the molecule in the pathogenesis of the disease.

CT60 and +49 polymorphisms of CTLA 4 are associated with ANCA-positive small vessel vasculitis

To investigate whether single nucleotide polymorphisms (SNPs) within cytotoxic T-lymphocyte antigen-4 (CTLA-4) are associated with ANCA-associated small vessel vasculitis (SVV). The CTLA-4 CT60 (exon 4), +49 (exon 1) and -318 (promoter region) genotypes were determined by PCR and restriction fragment length polymorphism (RFLP) in 222 white Caucasians of UK origin with SVV and 670 ethnically matched controls. The CTLA-4 exon 1 (+49) and 4 (CT60) polymorphisms are associated with SVV (+49: chi(2) = 10.965, P = 0.004; CT60: chi(2) = 12.017, P = 0.002). Both disease-susceptible and disease-protective haplotypes have been identified in this cohort, and their frequencies are similar in the subtypes of WG and microscopic polyangiitis. This study provides further evidence that CTLA-4, a susceptibility locus for a number of common autoimmune diseases, may also be involved in the development of ANCA-associated SVV.

CTLA-4 CT60 Polymorphism in Thyroid and Polyglandular Autoimmunity

Autoimmune thyroid diseases (AITDs) frequently occur together with other endocrine autoimmune conditions, denominated as polyglandular autoimmunity (PGA). The cytotoxic T-lymphocyte antigen 4 (CTLA-4) gene was recently associated with AITD and PGA, and the CTLA-4 protein is a strong inhibitor of T-cells.The tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine. This study aimed to analyze the association of the CTLA-4 CT60 and TNF-alpha-863 polymorphisms with PGA. Homogeneous groups of 70 patients with AITD, 70 with type 1 diabetes (T1D), 70 with both AITD and T1D (PGA), and 100 healthy controls were genotyped for the CTLA-4 CT60 and TNF-alpha-863 polymorphisms by minisequencing on an ABI PRISM-3100 genetic analyzer. The CT60 G/G genotype was significantly more common in patients with PGA than in healthy controls (48.6 % vs. 32.0 % , OR = 2.01, 95 % CI = 1.07-3.77, p = 0.038). The CT60 allele frequencies differed as well between PGA patients and controls, with the predisposing G allele being increased in PGA (OR = 1.63, 95 % CI = 1.03-2.55, p = 0.042). Patients with PGA did not differ from those with AITD (p = 0.602) or T1D(p = 0.362). For TNF-alpha-863, carriers of the minor A allele occurred more frequently in the T1D group than in controls (47.1 % vs. 33 % , OR = 1.81, 95 % CI = 0.97-3.39, p = 0.079), but no differences in allele or genotype distribution were noted between PGA patients and controls (p = 0.886 and 0.389, respectively). In conclusion the CTLA-4 CT60 polymorphism is associated with PGA.

CTLA-4 genotype and relapse incidence in patients with acute myeloid leukemia in first complete remission after induction chemotherapy

The recently described single-nucleotide polymorphism CT60, located in the 3'-untranslated region of the CTLA4 (cytotoxic T-lymphocyte antigen 4 ) gene, has been associated with susceptibility to several autoimmune diseases and has also been shown to be involved in immune responses following allogeneic stem cell transplantation (SCT). However, the contribution of the CTLA4 genotype to the control of minimal residual disease in patients with acute myeloid leukemia (AML) has yet to be explored. We investigated the association between the CTLA4 CT60 A/G genotype and the incidence of leukemic relapse in 143 adult patients with AML in first complete remission after the same chemotherapy protocol (CETLAM LAM'03). The CT60 AA genotype was associated with a higher rate of leukemic relapse (56.4 vs 35.6%, P=0.004; hazard ratio (HR)=2.64, 95% confidence interval (CI)=1.36-5.14) and lower overall survival at 3 years (39.4 vs 68.4%, P=0.004; HR=2.80, 95% CI=1.39-5.64). This is the first study to report an association between polymorphisms at CTLA-4 and AML relapse.

CBLBvariants in type 1 diabetes and their genetic interaction withCTLA4

Type 1 diabetes (T1D) is a multifactorial disease with genetic and environmental components involved. Recent studies of an animal model of T1D, the Komeda diabetes-prone rat, have demonstrated that the Casitas-B-lineage lymphoma b (cblb) gene is a major susceptibility gene in the development of diabetes and other autoimmune features of this rat. As a result of the inhibitory role of Cbl-b in T cell costimulation, dysregulation of Cbl-b may also contribute to autoimmune diseases in man. Different isoforms of Cbl-b exist; we evaluated expression levels of two known transcript variants. Constitutive expression of both isoforms was demonstrated, as well as an increased expression, after cytokine exposure, of an isoform lacking exon 16, suggesting a possible role of this variant in the pathogenesis of autoimmunity. We screened coding regions of the human CBLB gene for mutations in a panel of individuals affected with several autoimmune diseases. Eight single nucleotide polymorphisms (SNPs) were detected. One SNP in exon 12 of the CBLB gene was significantly demonstrated to be associated to T1D in a large Danish T1D family material of 480 families. Evidence for common genetic factors underlying several autoimmune diseases has come from studies of cytotoxic T lymphocyte antigen 4 (CTLA4), which encodes another negatively regulatory molecule in the immune system. Gene-gene interactions probably play substantial roles in T1D susceptibility. We performed stratification of CBLB exon 12 SNP data, according to an established CTLA4 marker, CT60, and evidence for a genetic interaction between the CTLA4 and CBLB genes, involved in the same biological pathway of T cell receptor signaling, was observed.

Cytotoxic T‐lymphocyte antigen‐4‐CT60 polymorphism in rheumatoid arthritis

Cytotoxic T-lymphocyte antigen-4 (CTLA-4) is a functional candidate gene with susceptibility to rheumatoid arthritis (RA). The aim of this work was to investigate the possible influence of the recently described CT60A/G dimorphism of the CTLA-4 gene in the susceptibility to RA in Spanish patients. A total of 433 RA patients and 398 control subjects were included in the study. Genotyping of CTLA-4 CT60 was performed using two different methods: polymerase chain reaction restriction fragment length polymorphism system using an amplification-created restriction site and a TaqMan 5'-allelic discrimination assay. In order to validate results obtained by different methods, a quality-control exercise was performed. No significant deviation in the distribution of the alleles or genotypes of the CT60 was found when we compared RA patient and control groups. In addition, no differences in CTLA-4 CT60 genotypic distribution was found when RA patients and controls were stratified by the presence or absence of the shared epitope. In conclusion, our results do not support an association between CT60A/G polymorphism and susceptibility to RA in the Spanish population, although the contribution of other positions located within the 3' region of the CTLA-4 gene to RA susceptibility cannot be discarded.

Analysis of immune regulatory genes in familial and sporadic Graves' disease.

Graves' disease (GD) is seen in apparently sporadic and familial forms. At least two immune regulatory genes are associated with GD, human leukocyte antigen (HLA) and cytotoxic T lymphocyte antigen-4 (CTLA-4). The aim of our study was to examine the contributions of HLA and CTLA-4 to the familial clustering of GD by analyzing them for association with familial and sporadic GD. We analyzed 160 Caucasian GD patients (69 familial and 91 sporadic), and 150 matched controls. Analysis of all GD patients demonstrated significant associations between GD and HLA-DR3 [P = 9.0 x 10(-7); relative risk (RR) = 3.8] and two CTLA-4 single nucleotide polymorphisms (SNPs), A/G(49) SNP (P = 0.03; RR = 1.5), and CT60 SNP (P = 0.03; RR = 1.4). Moreover, there was evidence for joint susceptibility to risk between HLA-DR3 and CTLA-4, giving a combined RR of 5.9. Subset analysis demonstrated no significant difference between the frequencies of HLA-DR3 and the susceptibility alleles of CTLA-4 A/G(49) and CT60 SNPs in the familial and sporadic GD subsets (P > 0.05). These results suggested that HLA-DR3 and CTLA-4 conferred a general increased risk for GD in both the sporadic and familial forms, and that the risk conferred by them was additive. However, HLA-DR3 and CTLA-4 did not have a stronger effect in the familial GD patients, suggesting that additional genes must contribute to the aggregation of GD within families.