Significance of tumor necrosis factor microsatellite polymorphism in renal transplantation

Linkage disequilibria between human leucocyte antigen-B and closely linked microsatellites in the Croatian population

The aim of the present study was to investigate polymorphism of D6S2927, STR_MICA, D6S2793, TNFa (D6S2792), TNFb and TNFd (D6S2789) microsatellites and linkage disequilibria between these loci and human leucocyte antigen (HLA)-B (previously tested) for better characterisation of extended HLA haplotypes. A total of 176 healthy unrelated Croatians were studied using polymerase chain reaction amplification and electrophoresis on 6% polyacrylamide gel in ALFexpress sequencer. Eight HLA-B/D6S2927 haplotypic associations (B*07/D6S2927-4, B*08/D6S2927-3, B*18/D6S2927-3, B*27/D6S2927-1, B*35/D6S2927-5, B*38/D6S2927-4, B*51/D6S2927-2 and B*61/D6S2927-1) showed strong association (P < 0.001, D > 0.5). Among 88 different HLA-B/STR_MICA haplotypic associations, seven combinations (B*07/STR_MICA-A5.1, B*08/STR_MICA-A5.1, B*15/STR_MICA-A5, B*18/STR_MICA-A4, B*27/STR_MICA-A4, B*38/STR_MICA-A9 and B*51/STR_MICA-A6) demonstrated high linkage (D> or = 0.3) with significant P value (P < 0.001). Strong associations were also observed for five HLA-B/D6S2793 haplotypes (B*07/D6S2793-CA17, B*08/D6S2793-CA24, B*13/D6S2793-CA18, B*14/D6S2793-CA14 and B*27/D6S2793-CA14). HLA-B*08/TNFb3 and HLA-B*50/TNFb7 were the strongest associations for HLA-B/TNFb. Nine HLA-B/TNFa combinations were observed with significant P value (B*07/TNFa11, B*08/TNFa2, B*13/TNFa7, B*18/TNFa10, B*27/TNFa6, B*37/TNFa9, B*38/TNFa10, B*39/TNFa13 and B*44/TNFa4). Out of six HLA-B/TNFd haplotypic associations with strong D value, HLA-B*08/TNFd2 and B*37/TNFd3 showed the highest statistical significance (P < 0.0001). These results provide data on the region around the HLA-B that is very attractive because of its contribution to genetic susceptibility for many HLA-associated diseases and therefore this information will help in all further HLA-B locus-associated disease studies.

TNF-alpha and TGF-beta1 gene polymorphisms and renal allograft rejection in Koreans

This study was performed in order to evaluate the association of tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) gene polymorphisms with renal allograft rejection in Koreans. Five TNF-alpha (-1031T/C, -863C/A, -857C/T, -308G/A and -238G/A) and two TGF-beta1 (codon 10 T/C and codon 25 G/C) single-nucleotide polymorphism (SNP) sites were studied by using polymerase chain reaction (PCR) single-strand conformation polymorphism and PCR restriction fragment length polymorphism methods in 100 controls and 164 patients. The patients underwent renal transplantation, having one or more Human leukocyte antigen (HLA)-A, HLA-B and HLA-DR antigens mismatched with their donors. For the TGF-beta1 gene, we also studied the polymorphism of donors. The allele frequencies of each SNP site in controls were not different from those of patients. The frequency of TNF-alpha high-producer genotype, -308GA, and TGF-beta1 lower (intermediate)-producer genotype, codon 10 CC and codon 25 GG, were significantly higher in patients with recurrent acute rejection episodes (REs), compared to those in patients with no or one RE. The highest risk group for developing recurrent REs showed the combination of TNF-alpha high- and TGF-beta1 lower-producer genotypes. Analysis of chronic renal allograft dysfunction (CRAD) revealed that TGF-beta1 high-producer genotype of donors, codon 10 TT/TC and codon 25 GG, is associated with CRAD especially in patients with recurrent REs. The highest risk group for developing CRAD showed the combination of recipient's TNF-alpha high- and donor's TGF-beta1 high-producer genotypes. These results would be useful for predicting high-risk group for acute rejection or CRAD in renal transplantation.

Cytokine Gene Polymorphisms and Risks of Acute Rejection and Delayed Graft Function after Kidney Transplantation

BACKGROUND

Pretransplantation identification of patients at an increased risk for adverse events would allow more individualized treatment strategies possibly improving long-term outcome. We studied cytokine gene polymorphisms of kidney allograft recipients and their donors to identify factors predisposing for acute rejection (AR) and delayed graft function (DGF).

METHODS

A total of 291 adult cadaver kidney recipients transplanted at a single transplantation centre between 1999 and 2002 were investigated. Recipients and donors were typed for TNF-alpha(-308G/A), TGF-beta1(codon 10T/C, codon 25C/G), IL-10(-1082G/A, -819C/T, -592C/A), IL-6(-174C/G), and IFN-gamma(+874T/A) polymorphisms using a SSP-PCR kit. An AR episode was defined based on clinical and histological findings (Banff criteria). RESULTS.: The incidence of AR was 17%. In univariate statistical analyses recipients with TNF-alpha -308AA-genotype were found to be at a significantly increased risk for rejection (odds ratio [OR] 5.0, 95% CI 3.0-8.3, P = 0.003). The association was independent from the patient-donor HLA-mismatch status. In addition, patients with IL-10 ACCACC, ATAATA, GCCATA (-1082A/G, -819C/T, -592C/A, respectively) haplotypes were predisposed to rejection (OR 1.9, 95% CI 1.1-3.1, P = 0.016). Further, the combination of recipient TGF-beta1 25GG-genotype and donor IL-10 -819T-allele was associated with rejection (OR 1.8, 95% CI 1.1-3.0, P = 0.027). These variables remained significant risk factors also in a multivariate logistic regression analysis. The incidence of DGF was 22%. The risk was increased by a donor TNF-alpha -308GA-genotype (OR 1.6, 95% CI 1.1-2.6, P = 0.040).

CONCLUSIONS

Our results confirm that cytokine gene polymorphisms influence the outcome of kidney transplantation. Our data especially identify the TNF-alpha -308AA-genotype as a factor predisposing for AR episodes.

Renovascular disease is associated with low producer genotypes of the anti-inflammatory cytokine interleukin-10

Cytokines are important mediators of inflammatory and proliferative responses in disease states including atherosclerosis. Genetic variations in cytokine production could potentially influence the outcome of these responses. The aim of this study was to determine whether cytokine gene polymorphism might influence the development of atherosclerotic renal artery stenosis. Sixty-six patients with atherosclerotic renal artery stenosis and 100 normal healthy individuals were genotyped for interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-2 promoter region polymorphism. TNF-a, TNF-d, and IL-10 microsatellite polymorphisms were also analyzed. The frequency of the anti-inflammatory cytokine IL-10 promoter (-1082 A positive) GA and AA genotypes which are associated with low production were higher in the patient group when compared to the control group. The AA-TT-AA homozygous genotype combination of three single-nucleotide polymorphisms at -1082, -819, and -592 in the IL-10 gene was also observed at a higher frequency in the patient group compared to the controls. The frequency of TNF-alpha, IL-6, and IL-2 polymorphisms did not show any significant difference between the patient and control groups. To correlate IL-10 genotypes with differences in IL-10 protein expression, in vitro mRNA and protein levels were analyzed in lipopolysaccharide-stimulated peripheral blood mononuclear cells from 22 patients with renal artery stenosis and 33 controls. Individuals genotyped as A positive at position -1082 produced lower levels of IL-10 protein and had lower copy numbers of mRNA when compared to individuals genotyped as A negative in both patient and control groups. The increased frequency of the low producer IL-10 promoter, -1082 A-positive genotype in patients with renal artery stenosis, suggests that IL-10 may protect against the development of atherosclerotic renovascular disease.

Polymorphisms of the tumour necrosis factor alpha gene at position -308 and TNFd microsatellite in primary IgA nephropathy

BACKGROUND

The development of glomerular inflammation in immunoglobulin A nephropathy (IgAN) has been associated with various cytokines, including tumour necrosis factor alpha (TNFalpha). A biallelic polymorphism in the promoter region of the TNFalpha gene (TNFA), at position -308, has been described (TNFA-1 and TNFA-2) and is associated with increased TNFalpha production for the TNFA-2 allele. Another microsatellite polymorphism has been described for TNFd, which is functional and associated with increased production of TNFalpha for the d3 allele.

METHODS

We have studied these two polymorphisms in 242 Caucasian patients with biopsy-proven IgAN (169 male, 73 female), who were followed from 1990 to 1999, and in 210 appropriate local Caucasian controls (133 male, 77 female) for comparison of genotypes and allelic distribution.

RESULTS

The respective frequencies of A1/A1, A1/A2 and A2/A2 TNFA genotypes were 76.4, 22.3 and 1.3% in IgAN vs 78.1, 19.5 and 2.4% in controls (P=NS). For TNFd, the frequencies of the respective genotypes d3/d3, d3/non-d3 and non-d3/non-d3 were significantly different (chi(2)=12.30, P=0.002, Pc=0.013) with an increased frequency of the low-producer genotype non-d3/non-d3 in IgAN patients (24 vs 12%). The combination of TNFA and TNFd polymorphisms demonstrated that compared with controls, patients with non-A2 and non-d3 alleles (low producers) were more common (18 vs 9%; P=0.006). In the genotype/clinical phenotype correlations, we could not demonstrate significant differences between the different subgroups of patients. However, high-producer TNFalpha patients (A2 and d3 alleles) had more chronic renal failure than others (36.6 vs 22.9%) at last follow-up and their survival without chronic renal failure (Kaplan-Meier) was lower. Nevertheless, TNFalpha polymorphisms were not an independent risk factor for the progression of the disease.

CONCLUSIONS

TNFA and TNFd polymorphisms seem to influence the occurrence or initiation of the disease, but do not play a significant role, if any, in the progression of IgA nephritis.

Genetic variability and transplantation

PURPOSE OF REVIEW

The purpose of this review is to summarize recent advances within the area of genetic polymorphisms with a specific emphasis on renal transplantation, and to discuss the potential clinical applications.

RECENT FINDINGS

Due to recent advances in molecular techniques, there has been an abundance of publications describing genetic variability in molecules relevant to transplant outcome. Many studies are now demonstrating associations between polymorphisms in these candidate genes and outcomes in organ transplantation.

SUMMARY

These studies emphasize the potential role of genetic variability in transplantation, and provide the rationale for large prospective studies to clearly define the potential benefits of genotyping in the risk stratification of transplant recipients.

Polymorphisms in the TNF region confer susceptibility to UVB-induced impairment of contact hypersensitivity induction in mice and humans

Acute, low-dose ultraviolet B radiation protocols impair induction of contact hypersensitivity (CHS) to highly reactive haptens in some mice and humans (UVB-susceptible) but not others (UVB-resistant). These deleterious effects of ultraviolet radiation appear to be mediated in part by tumour necrosis factor alpha (TNF-alpha), which is released from, or accumulates in, UVB-exposed skin. To test the hypothesis that a polymorphism of the Tnfa locus governs the UVB-S and UVB-R phenotypes, studies have been conducted in genetically disparate strains of mice. Mice carrying the Tnf(d) allele [with precisely 14 (CA) repeats in the promoter region] display the UVB-R phenotype, whereas mice with different Tnf alleles [with (CA) repeats of </>14] display the UVB-S phenotype. Molecular genetic studies of the TNF region of HLA in humans displaying either the UVB-S or UVB-R phenotype reveal a significant increase in the frequencies of TNFa2 in UVB-S individuals (P=0.00032) and of TNFd3 in UVB-R individuals (P=0.012). Moreover, DNA sequencing analyses of five single-nucleotide polymorphisms (SNPs) of the TNF promoter region revealed a significant increase in the frequency of TNF/-863A (P=0.015). We propose that the TNF region dictates susceptibility to the deleterious effects of UVB radiation on the induction of contact hypersensitivity in both mice and humans, and that the UVB-S-promoting polymorphisms significantly promote the risk of sunlight-induced skin cancer in humans.

Tumor necrosis factor microsatellite alleles in patients with rheumatoid arthritis in Taiwan

OBJECTIVE

To investigate the association of tumor necrosis factor (TNF) microsatellite alleles with the pathogenesis of rheumatoid arthritis (RA) in Taiwan.

METHODS

The TNF a, b, c, d, and e microsatellites were determined in 112 patients with RA and 99 healthy controls by using polymerase chain reaction (PCR) and electrophoresis with sequencing gel. All of these patients and controls had known HLA-DR genotypes and TNF-308 polymorphisms.

RESULTS

The phenotypic frequency of TNFa9 was significantly higher in DR4(-) RA patients than in DR4(-) controls. However, the phenotypic frequency of TNFb6 was significantly higher in RA patients than in controls in the presence of HLA-DR4. The phenotypic frequency of TNFa3-e1 was significantly lower in DR4(+) RA patients than in DR4(+) controls, while a negative linkage disequilibrium was noted between TNFa3-e1 and HLA-DR4. TNF microsatellite alleles were not related to the prevalences of bone erosion, rheumatoid nodule, sicca syndrome, pulmonary fibrosis, and seropositivity of rheumatoid factor (RF) in patients with RA.

CONCLUSION

The associations of TNF microsatellites with the susceptibility to RA in Taiwan are not completely independent of the HLA-DR associations. The association of TNFb6 with the susceptibility to RA depends on the presence of HLA-DR4, and the correlation of TNFa9 to RA depends on the absence of HLA-DR4. The negative association of TNFa3-e1 with RA may be secondary to the negative linkage disequilibrium between TNFa3-e1 and HLA-DR4. Moreover, TNFb6 and HLA-DR4 have a synergistic effect on the susceptibility to RA. TNFa3-e1 and TNF-308A have a synergistic effect on preventing from RA. The TNF microsatellite alleles are not related to the clinical manifestations and severity of RA patients in Taiwan.

Influence of TNFalpha gene polymorphisms on TNFalpha production and disease

Tumor necrosis factor alpha (TNFalpha) is a potent inflammatory cytokine. In human, the TNFalpha gene is located within the highly polymorphic major histocompatibility complex (MHC) region on chromosome 6p21.3. TNF gene cluster contains many polymorphisms including microsatellites and single nucleotide polymorphisms (SNPs). Many of these polymorphisms were found to be in linkage disequilibrium with HLA class I and II alleles. Some of the TNFalpha gene polymorphisms were found to influence TNFalpha production in vitro, for example the -308 SNP. Many studies have shown that this SNP and others within the TNFalpha gene associate with different inflammatory conditions. Whether this phenomenon is due to the direct influence of the SNP in question and/or due to linkage disequilibrium with other polymorphisms within the TNFalpha gene or the HLA system is still controversial.

Cytokine polymorphic analyses indicate ethnic differences in the allelic distribution of interleukin-2 and interleukin-6

BACKGROUND

Polymorphisms in the regulatory regions of cytokine genes affect protein production and are associated with allograft outcome. Ethnic origin has been identified as a significant prognostic factor for several immune-mediated diseases and for outcome after allotransplantation. A clear relationship between cytokine polymorphisms and ethnicity has not been shown.

METHODS

One hundred sixty subjects including 102 whites and 43 African-Americans were studied. Using polymerase chain reaction-based assays and, in some cases, restriction enzyme digestion, we determined genetic polymorphisms for the cytokines interleukin (IL) -2, IL-6, IL-10, tumor necrosis factor-alpha, transforming growth factor-beta, and interferon-gamma (IFN-gamma). Genetic polymorphism frequencies were then compared to ethnicity using chi-square analysis and Fisher's exact two-tailed tests.

RESULTS

For both the IL-2 and IL-6 genes, we found that whites and African-Americans differed significantly (P <0.05) in their allelic distribution and genotype frequency. A trend toward ethnic distribution was noted among the alleles and genotypes for the IL-10 and IFN-gamma genes. We found no correlation between ethnicity and either allelic distribution or genotype frequency for the tumor necrosis factor-alpha or transforming growth factor-beta genes. When comparisons were made between patients with or without a history of kidney failure, the allelic or genotypic distributions for the IL-6 and IFN-gamma genes were found to significantly differ.

CONCLUSIONS

Our work demonstrates a correlation between ethnicity and polymorphisms in several cytokine genes. In addition, we found that patients requiring renal transplantation differ from the general population with regard to certain cytokine gene polymorphisms. These findings may have relevance in making prognostic determinations or tailoring immunomodulatory regimens after renal transplantation.

Nutritional modulation of immune function

The inflammatory response to injury and infection, although an essential part of immune function, carries the risk of severe tissue depletion and immunosuppression. These outcomes increase morbidity and delay recovery. Evidence is accumulating that single-nucleotide polymorphisms in the genes controlling pro-inflammatory cytokine production adversely influence the response. Immunonutrition provides a means of modulating the inflammatory response to injury and infection, and thereby improves clinical outcome. n-3 Polyunsaturated fatty acids (n-3 PUFA), glutamine, arginine, S amino acids and nucleotides are important components of immunonutrient mixes. While animal model studies suggest that all these components may exert a beneficial effect in patients, the number of large randomized placebo-controlled trials utilizing immunonutrition is fairly limited and the observed effects are relatively small. Meta-analyses suggest that while immunonutrition may not reduce mortality rates, a reduction in hospital length of stay, decreased requirements for ventilation and lower infection rates are achieved by this mode of nutrition. The present paper discusses some underlying reasons for the difficulty in demonstrating the clinical efficacy of immunonutrition. Paramount among these reasons is the antioxidant status and genetic background of the patient. A number of studies suggest that there is an inverse relationship between inflammation and T-cell function. Immuno-enhancive effects have been shown in a number of studies in which n-3 PUFA, glutamine and N-acetyl cysteine have been employed. All these nutrients may exert their effects by suppressing inflammation; n-3 PUFA by direct suppression of the process and glutamine and N-acetyl cysteine by acting indirectly on antioxidant status. Glutamine and nucleotides exert a direct effect on lymphocyte proliferation. Preliminary data suggests that not all genotypes are equally sensitive to the effects of immunonutrition. When further studies have been conducted to discern the precise interaction between each individual's genotype of relevance to the response to injury and infection, and immunonutrients, the level of precision in the application of immunonutrition will undoubtedly improve.

A study of cytokine gene polymorphisms and protein secretion in renal transplantation

Although there is evidence that cytokine gene polymorphisms are associated with varying quantities of cytokine protein production, the exact role of these polymorphisms in allograft rejection remains unclear. In a previous study, we demonstrated a significant association between high IL-10 secretion in mixed lymphocyte culture (MLC), together with HLA mismatching for at least 4-6 antigens, with the occurrence of acute rejection following renal transplantation. We, therefore, wished to ascertain whether cytokine gene polymorphisms are associated with varying levels of protein secretion and/or allograft rejection in the same group of patients. Cytokine protein secretion in MLC for IL-4, IL-6, IL-10 and IFN-gamma was measured by ELISA in 49 patient-donor pairs. Protein secretion for the above cytokines was also measured in phytohaemagglutinin (PHA) stimulated cultures in 30 normal controls. In both patient and control groups, single nucleotide polymorphism analysis for IL-4 G(-590)T, IL-6 G(-174)C, IL-10 G(-1082)A, IL-10 C(-819)T, IL-10 C(-592)A, TNF-alpha G(-308)A and microsatellite analysis for IFNG (CA repeat) was performed. No correlation was found between cytokine gene polymorphisms and cytokine protein secretion in either mitogen stimulated cultures (control group) or MLC (patient group). In addition, no correlation was demonstrated between cytokine gene polymorphisms and renal allograft rejection.

Characterization of the promoter of human leukocyte-specific transcript 1. A small gene with a complex pattern of alternative transcripts

The gene for the human leukocyte-specific transcript 1 (LST1) encodes a small protein that modulates immune responses and cellular morphogenesis. The LST1 transcripts are expressed at high levels in dendritic cells. Because of the complex splicing pattern, use of alternative 5'-untranslated exons, and a biologically interesting pattern of expression of LST1 mRNA, we studied the human LST1 gene promoter and regulatory elements. We identified an additional upstream 5'-untranslated exon in U937 monocytic cells. Transient transfection studies demonstrated that the combination of regions from -1363 to -621 with -112 to -54, relative to the translation start codon, produced the highest level of transcripts from among the various constructs tested, but the pattern of transcripts produced was only a subset of those produced from the endogenous gene. DNase I footprinting analysis and electrophoretic mobility shift assays showed that oligonucleotide probes corresponding to three regions, -1171 to -1142 (BI), -1136 to -1111 (BII), and -783 to -751 (BIV), bound proteins in U937 nuclear extracts. Competition and supershift electrophoretic mobility shift assay did not identify any known transcription factors responsible for BII probe binding. These studies suggest that a novel DNA-binding site and interaction of multiple regulatory elements may be involved in mediating the expression of the various forms of LST1 mRNA.

Microsatellites in the HLA region: 1999 update

In this third update of a series of reviews on microsatellites in the HLA region or close to it we report 155 microsatellites, corresponding to 51 newly described markers, in addition to the 103 reported in the 1997 and 1998 reviews. This work is based both on a literature review and on data publicly available in molecular databases on the internet (http://www.gdb.org; http://bioinfo.weizmann.ac.il/cards/; http://cedar.genetics.soton.ac.uk/) up to September 1999. Thanks to numerous studies involving major histocompatibility complex (MHC) microsatellites, documentation on HLA region is proposed, including information on microsatellites described through MHC sequence projects and presenting documented location, polymorphism and amplification condition, together with additional information on previously described microsatellites when available and information on data in the literature regarding gametic associations between HLA region loci and alleles and microsatellite alleles. As basic information are presented various documents: i) a table showing the following characteristics of the 155 microsatellites: name, localisation, polymorphism, primer sequences, reference; ii) an integrated map of some HLA region genes and the 155 microsatellites considered; and iii) a summary table on HLA and microsatellites association patterns. In addition, an overview on HLA microsatellite analysis application is presented, with a special focus on disease genetics studies in the form of recent references where the use of microsatellites of the HLA region was a key tool. This review aims at providing the human immunogenetics community with a tool for helping optimal choice of microsatellites to be used in various studies.

LST1: a gene with extensive alternative splicing and immunomodulatory function

The gene of the leukocyte-specific transcript (LST1) is encoded within the TNF region of the human MHC. The LST1 gene is constitutively expressed in leukocytes and dendritic cells, and it is characterized by extensive alternative splicing. We identified 7 different LST1 splice variants in PBMC; thus, 14 LST1 splice variants (LST1/A-LST1/N) have been detected in various cell types. These isoforms code for transmembrane as well as soluble LST1 proteins characterized by two alternative open reading frames at their 3' end. We demonstrate the presence of the transmembrane variant LST1/C on the cell surface of the monocytic cell lines U937 and THP1. Recombinant expression of LST1/C permitted its profound inhibitory effect on lymphocyte proliferation to be observed. In contrast, the alternative transmembrane variant LST1/A, the extracellular domain of which shows no amino acid sequence homology to LST1/C exerted a weaker but similar inhibitory effect on PBMC. These data demonstrate the protein expression of LST1 on the cell surface of mononuclear cells, and they show an inhibitory effect on lymphocyte proliferation of two LST1 proteins although they have only a very short amino acid homology.

The importance of genetic polymorphisms in renal transplantation

Genetic variations including single nucleotide polymorphisms, dinucleotide repeats and microsatellites have been identified in a number of genes encoding cytokines, cytokine receptors, chemokines and their receptors, adhesion molecules. Several of the polymorphisms are located in the promoter region of the gene, affect transcription or translation, and not infrequently determine the level of expression of the protein product. An interesting and testable hypothesis for the clinical heterogeneity and differential responsiveness in allograft recipients is genetic variation. These nucleotide sequence variations, polymorphisms located in genes contributing to immune repertory and in genes responsible for drug metabolism, are excellent candidates for the differential clinical phenotype.

Influence of TNF microsatellite polymorphisms (TNFa) on age-at-onset of insulin-dependent diabetes mellitus

The TNF-alpha gene is located in the HLA region and has been implicated in the pathogenesis of Type I (insulin-dependent) diabetes mellitus (IDDM). We investigated the frequency of TNFa microsatellite alleles in 76 young-onset IDDM patients, 65 adult-onset IDDM patients, and 90 control subjects. We also examined the association of these TNFa alleles with HLA-DRB1 alleles, HLA-class I alleles, and TNF-alpha production. The frequency of the TNFa2 and TNFa9 alleles was increased in the young-onset IDDM patients compared to control subjects, but the increased frequency of TNFa2 was not significant after the correction for the number of comparisons was made. We did not find any association of TNFa2 or TNFa9 with any of the HLA-DRB1 alleles. In contrast, the frequency of the TNFa13 allele was decreased in both the young-onset and the adult-onset IDDM patients compared to the control subjects, but the difference lost significance after the correction was made in the adult-onset IDDM. The TNFa13 allele was strongly associated with DRB1*1502. Patients with TNFa2 or TNFa9 had greater TNF-alpha production, while those positive for TNFa13 had lower TNF-alpha production than patients with non-TNFa2, a9, and a13 alleles. These results suggest that TNFa polymorphisms are associated with age-at-onset of IDDM and influence the inflammatory process of pancreatic beta cell destruction in the development of IDDM.