Objective: Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation as a result of an exaggerated T-cell response. Cytotoxic T lymphocyte antigen-4 (CTLA-4) expressed mainly on activated T cells, inhibits T cell activation by combining B(7) through competing CD(28) and maintains immune system homeostasis. Polymorphisms in the CTLA-4 gene are known to be associated with several autoimmune diseases, but no studies related to IBD. The aim of the study is to investigate an association between CTLA-4 gene microsatellite polymorphisms and IBD.
Methods: Unrelated 68 Chinese Han patients with IBD (54 ulcerative colitis and 14 Crohn's disease) and 140 healthy controls were studied. The (AT)n repeat sequence in the 3' untranslated region of exon 4 were amplified by allele-specific PCR. The amplified products were electrophorosised by 12% polyacrylamid gel and followed by silver staining.
Results: Eighteen alleles of CTLA-4 microsatellite were found in Chinese patients and healthy individuals. Long allele, 122bp was apparently increased in patients with ulcerative colitis compared with healthy controls (7.4% vs 0.3%, P = 0.0002/Pc = Sig, OR = 22.32, 95% CI: 2.76 - 180.80).
Conclusion: CTLA-4 gene microsatellite polymorphism was strongly associated with ulcerative colitis in Chinese Han patients in Hubei province.