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Multiple sclerosis (MS) is presumed to be an autoimmune disease of the central nervous system leading to demyelination, axonal damage, and progressive neurologic disability. Although no single animal model can capture all aspects of human MS, the experimental autoimmune encephalomyelitis (EAE) model in rodents immensely improved our understanding of MS pathophysiology. The main advantage of EAE is the genetic engineering of mice to allow researchers to investigate the roles of various genes/molecules in the disease. Data generated from EAE models suggest that disease onset results from an aberrant, T cell-mediated immune response to a number of myelin antigens. We also discuss the importance of other immune cells, such as CD8+ T cells, B cells, and macrophages, in the immunopathogenesis of the disease. In summary, the EAE model has helped to elucidate the roles of various cells/molecules in the neuro-inflammatory aspects of MS.

Population studies have shown that among all the genetic factors linked with autoimmune disease development, MHC class II genes on chromosome 6 accounts for majority of familial clustering in the common autoimmune diseases. Despite the highly polymorphic nature of HLA class II genes, majority of autoimmune diseases are linked to a limited set of class II-DR or -DQ alleles. Thus a more detailed study of these HLA-DR and -DQ alleles were needed to understand their role in genetic predisposition and pathogenesis of autoimmune diseases. Although in vitro studies using class-II restricted CD4 T cells and purified class II molecules have helped us in understanding some aspects of HLA class-II association with disease, it is difficult to study the role of class II genes in vivo because of heterogeneity of human population, complexity of MHC, and strong linkage disequilibrium among different class II genes. To overcome this problem, we pioneered the generation of HLA-class II transgenic mice to study role of these molecule in inflammatory disease. These HLA class II transgenic mice were used to develop novel in vivo disease model for common autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, insulin-dependent diabetes mellitus, myasthenia gravis, celiac disease, autoimmune relapsing polychondritis, autoimmune myocarditis, thyroiditis, uveitis, as well as other inflammatory disease such as allergy, tuberculosis and toxic shock syndrome. As the T-cell repertoire in these humanized HLA transgenic mice are shaped by human class II molecules, they show the same HLA restriction as humans, implicate potential triggering mechanism and autoantigens, and identify similar antigenic epitopes seen in human. This review describes the value of these humanized transgenic mice in deciphering role of HLA class II molecules in immunopathogenesis of inflammatory diseases.