The Implications of HLA Phenotypes in Inflammatory Bowel Disease

Abstract

Susceptibility to Inflammatory Bowel Disease (IBD) is, in part, genetically determined, and the HLA genes are candidate for a role in the genetic susceptibility to this disease, because their products play a central role in the immune responses. Multiple studies have reported associations between HLA phenotypes and either Ulcerative Colitis (UC) or Crohn's Disease (CD), the major two disorders of IBD, but much of these data are still controversial. To estimate overall associations between HLA phenotypes and this disease, and to establish the probable etiologic or protective functions conferred by these molecules, a total of 71 Iraqis, Arabs patients (55 with UC and 16 with CD) compared with ethnically matched, 70 healthy control group were assayed for a panel of monoclonal antibodies for HLA class I and II, using microlymphocytotoxicity test. Among class I molecules; A23, A(16+66), and B27, were positively associated with the disease (Odds ratio: 18.9, 9.4, and 4.8, respectively), conferred etiologic roles. The DQ2 was the only one of class II molecules that played same role (OR 2.6). On the other hand, A2, Bw4, Cw5, DR3, and DR8, were found to be negatively associated with IBD suggesting a protective role at respective ORs; 0.4, 0.1, 0.2, 0.1, and 0.3. Thus, IBD is associated with specific class I and II molecules that may play roles in the etiology or in prevention of this disease. Further studies required to determine allelic variants of HLA-genes in this study.