Association of Autoimmune Pancreatitis With Cytotoxic T-lymphocyte Antigen 4 Gene Polymorphisms in Japanese Patients

OBJECTIVES: Autoimmune pancreatitis (AIP) is characterized by high serum IgG4 concentrations, lymphoplasmacytic inflammation, and a favorable response to corticosteroid treatment. Although the HLA DRB1*0405-DQB1*0401 haplotype and Fc receptor-like 3 polymorphisms have been associated with AIP, the role of other genetic factors is largely unknown. As cytotoxic T-lymphocyte antigen 4 (CTLA4) polymorphisms have recently been linked with several autoimmune diseases, we sought to determine if CTLA4 polymorphisms and serum sCTLA4 levels were associated with AIP as well. METHODS: Five CTLA4 polymorphisms, located at -1722, -658, and -318 in the promoter, +49 in exon 1, and +6230 in the 3' untranslated region, were genotyped in 59 patients with AIP and 102 healthy subjects. Serum sCTLA4 levels were also determined in cohorts of 52 patients and 32 controls. RESULTS: Compared with healthy subjects, we found a significant increase in the +6230 G/G genotype (64% vs 42%, odds ratio [OR] 2.48, P = 0.011) in AIP patients. Haplotype 2, which had the +6230A, was associated with AIP resistance (OR 0.49, P = 0.011). The +49A/A and +6230A/A genotypes were associated with an enhanced risk of relapse (OR 5.45, P = 0.038 and OR 12.66, P = 0.022). Additionally, median serum sCTLA4 levels were significantly higher in patients with AIP (8.9 ng/mL) compared with healthy subjects (2.9 ng/mL, P < 0.001). The +6230 G/A polymorphism did not influence sCTLA4 levels in AIP patients. CONCLUSIONS: Our findings suggest that AIP is associated with a genetic polymorphism in CTLA4 and is positively correlated with serum sCTLA4 levels. (Am J Gastroenterol 2008;103:588-594).