The association of insulin-dependent diabetes mellitus (IDDM) with certain HLA alleles is well documented in pediatric patients. Whether a similar association is found in adult-onset IDDM is not clear, although the disease occurs after the age of 20 in 50% of cases. HLA class II DRB1, DQA1, and DQB1 alleles were studied in 402 type I diabetics and 405 healthy controls (all Caucasian) using oligonucleotide typing after gene amplification. Alleles DRB1 *03, DRB1 *04, DQB1 *0201, DQB1 *0302, DQA1 *0301, and DQA1 *0501 were indeed enriched in diabetics and the highest relative risk was observed in patients carrying both the DRB1 *03-DQB1 *0201 and the DRB1 *0402 or DRB1 *0405-DQB1 *0302 haplotypes. However none of these alleles, or specific residues, could alone account for the susceptibility to IDDM. Furthermore, there were major differences in HLA class II gene profiles according to the age of onset. Patients with onset after 15 yr (n = 290) showed a significantly higher percentage of non-DR3 /non-DR4 genotypes than those with childhood onset (n = 112) and a lower percentage ofDR3 /4 genotypes. These non-DR3 / non-DR4 patients, although presenting clinically as IDDM type 1 patients, showed a lower frequency of islet cell antibodies at diagnosis and a significantly milder initial insulin deficiency. These subjects probably represent a particular subset of IDDM patients in whom frequency increases with age. The data confirm the genetic heterogeneity of IDDM and call for caution in extrapolating to adult patients the genetic concepts derived from childhood IDDM. (J. Clin. Invest. 1992. 90:2242-2250

Autoimmune hepatitis (AIH) is characterized by an immune-mediated injury of the hepatic parenchyma of unknown pathogenesis. Type 2 AIH is identified by the presence of antiliver-kidney microsomes type 1 (anti-LKM1) and anti-liver cytosol type 1 (anti-LC1) autoantibodies. The current study shows that a murine model of AIH can be generated by DNA immunization against type 2 AIH self-antigens (P450 2D6 and formiminotransferase-cyclodeaminase). A pCMV plasmid containing the N-terminal region of mouse CTLA-4 and the antigenic region of human CYP2D6 (672-1,377 bp) and human formiminotransferase cyclodeaminase (FTCD; 1,232-1,668 bp) was used for DNA immunization of C57BL/6 female mice. Immunized mice showed elevated levels of alanine aminotransferase (ALT), with peaks at 4 and 7 months postinjection. Periportal, portal, and intralobular liver inflammatory infiltrates were observed at histology. Mainly CD4؉ lymphocytes, but also CD8؉ and B lymphocytes, were found in the liver. Cytotoxic-specific T cells were found in both the liver and spleen of these animals. Mice developed anti-LKM1 and anti-LC1 antibodies of immunoglobulin G2 (IgG2) subclass, against specific mouse autoantigens. The ALT levels correlated with both the presence of anti-LKM1/anti-LC1 antibodies and the presence of liver necroinflammation. In conclusion, in mice, DNA immunization against human autoantigens breaks tolerance and induces an autoimmune liver disease. Molecular mimicry between foreign and self-antigens explains the liver injury. This model of AIH resembles human type 2 AIH and will be helpful for the study of its pathogenesis. (HEPATOLOGY 2004;39: -1074.)A utoimmune hepatitis (AIH) is a disorder of unknown etiology characterized by an immune-mediated injury that gradually destroys the hepatic parenchyma. Most patients have circulating autoantibodies, which are considered to be specific markers of the disease. 1 Two types of AIH are recognized, according to the autoantibodies found in sera samples. Type 1 AIH is characterized by the presence of anti-smooth muscle and/or anti-nuclear antibodies, whereas type 2 AIH shows anti-liver-kidney microsomal type 1 (anti-LKM1) and/or anti-liver cytosol type 1 (anti-LC1) antibodies. [2][3][4] Previous work has shown that the target of LC1 antibodies is formiminotransferase cyclodeaminase (FTCD) 5 and that anti-LKM1 antibodies are directed against P450 2D6 (CYP2D6). 6 These two enzymes are mainly expressed in hepatocytes. Titers of these autoantibodies show a good correlation with AIH activity and it has been speculated that they might play a role in the pathogenesis of this inflammatory disease. 7 Information obtained from clinical data can be applied to develop an animal model that will give new and broader insights into the relative importance of different factors involved in the pathogenesis of AIH.Several murine models of AIH have been described, but none of them are completely satisfactory. One of these models showed the development of a subacute hepatitis after immunization with a liver subcellular...

Background-Susceptibility to coeliac disease is strongly associated with particular HLA class II alleles. However, non-HLA genetic factors are likely to be required for the development of the disease. Among candidate genes is the CTLA-4 (cytotoxic T lymphocyte associated) gene located on chromosome 2q33 in humans, which encodes a cell surface molecule providing a negative signal for T cell activation. Aims-To investigate CTLA-4 exon 1 polymorphism (position 49 A/G) in patients with coeliac disease. Patients-101 patients with coeliac disease and 130 healthy controls.Methods-Allele specific hybridisation and restriction enzyme digestion of polymerase chain reaction amplified genomic DNA. Results-The A allele of the CTLA-4 position 49 polymorphism was found on 82.2% of chromosomes in patients with coeliac disease compared with 65.8% in controls (p<0.0001), mostly in the homozygous form (68.3% in patients versus 47.7% in controls; odds ratio (OR) 2.36, 95% confidence interval (CI) 1.37 to 4.06, p=0.002). Four patients only had the G/G genotype compared with 21 controls (OR 0.21, CI 10.07 to 0.64, p=0.002). These diVerences were maintained when subjects were stratified according to the HLA class II phenotype, in particular when patients and controls were matched for the presence of the predisposing HLA DQB1*02 (DQ2) allele or HLA-DQA1*0501/ DQB1*02 heterodimer. Conclusion-The CTLA-4 gene polymorphism is a non-HLA determinant that predisposes to coeliac disease. Whether it directly contributes to disease susceptibility or represents a marker for a locus in linkage disequilibrium with CTLA-4 needs further investigation.

Understanding the pathogenesis of autoimmune hepatitis requires an animal model in which chronic progressive immune injury develops spontaneously or with minimal manipulations. The new transgenic mouse model proposed in this study is based on the hypothesis that infectious agents have the potential to initiate autoreactivity through molecular mimicry. A transgenic mouse expressing lymphocytic choriomeningitis virus nucleoprotein (NP) in a H-2b background developed liver injury when vaccinated with plasmids expressing NP as an intracellular or a secretory protein. Coinjection of plasmids coding for NP and IL-12 facilitated the induction of a Th1 phenotype as detected by a specific B lymphocyte response characterized by a predominance of IgG2 subclass anti-NP Abs. CTLs activated in peripheral lymphoid organs by DNA vaccination migrated to the periportal and lobular areas of the liver. Their presence was associated with a significant degree of cytolysis, as evidenced by elevated transaminases several weeks after immunization. As activated specific T lymphocytes proliferated in the periphery and caused cytolysis of target cells, this study suggests that autoimmune hepatitis can be triggered by molecular mimicry, and that local injury may not be essential to initiate autoreactivity in the liver.

Background-Susceptibility to coeliac disease is strongly associated with particular HLA class II alleles. However, non-HLA genetic factors are likely to be required for the development of the disease. Among candidate genes is the CTLA-4 (cytotoxic T lymphocyte associated) gene located on chromosome 2q33 in humans, which encodes a cell surface molecule providing a negative signal for T cell activation. Aims-To