HLA-DR-DP and -DQ Antigens in Coeliac Disease

Abstract

Population studies in different countries have confirmed the association of coeliac disease (CD) with the HLA class II molecules HLA-DR3 and -DR7, and with the HLA-DR phenotypes DR3/DR7, DR3/DR3 and DR5/DR7 Familystudies have also shown that CD segregates with these HLA-DR phenotypes. Among HLA-DR3-DR7 positive coeliac patients a 100% association of the disease with the HLA-class II molecule DQw2 has been described. Other reports have indicated an association between CD and some DP polymorphisms. Whether all those genes contribute to the susceptibility for CD or whether their association is secondary to the one with DQ is not known. One of the respects in which HLA-DQ molecules differ from HLA-DR ones is that both the a and the p chain genes are polymorphic in the HLA-DQ while polymorphism of the HLA-DR molecules is limited to the β chains. This is the reason why hybrid HLA-DQ molecules can result from genetranscomplementation. The HLA-DQw2 specificity is associated with two types of α/β dimers: DQ α 2.3/β 1.2 and with DQ α 2.7/β 2.7. On the other hand at DNA and at protein level it has been shown that CD is strongly associated with the HLA-DQ chains α 2.3, 2.7 and β 2.3. It has been speculated that the HLA-DQ α 2.3/β 2.7 or the HLA-DQ α 2.3/β 2.3 dimers are the class II molecules involved in the onset of CD.