HLA-B27 transgenic rats model.

To investigate the role of HLA-B27 in the pathogenesis of spondylarthropathies, rats transgenic for HLA-B27 and human beta 2-microglobulin were produced. Several lines of B27 transgenic rats spontaneously develop a multisystem inflammatory disorder reminiscent of human spondylarthropathies, with gut, joint, skin and male genital lesions. The role of HLA-B27 in this model was studied and it was found that a high expression level of the transgene in cells of hematopoietic origin was critical to induce inflammatory manifestations. Furthermore, a combined implication of CD4+ T cells and antigen presenting cells in this model is suspected, based on passive transfer studies, although a specific influence of HLA-B27 upon T cell education in the thymus is unlikely to be important. Beside the immune system, bacterial flora exerts an important influence in this model, as a triggering agent of gut and joint inflammation. Finally, endogenous rat genetic factors are suspected to be involved in this model.