| Research Abstract |
TNF gene is tightly linked to major histocompatibility complex in both human and mouse. In the promoter region of mouse TNFalpha gene, there is a simple sequence length polymorphism (microsatelite DNA polymorphism) among TNF haplotypes. To investigate the relationship between TNF polymorphism and the degree of TNF production, we introduced TNF^d haplotype from B10.PL(H-2^u : K^uA^uE^uTNF^dD^d) and NZB(H-2^d : K^dA^dE^dTNF^dD^d), and TNF^b haplotype from B6(H-2^b : K^bA^bE^bTNF^b) to NZW(H-2^z : K^uA^uE^uTNF^zD^z), and established NZW.PL(H-2^u : K^uA^uE^uTNF^bD^d), NZW.H-2^d(H-2^d : K^dA^dE^dTNF^dD^d) and NZW.H-2^b(H-2^u : K^uA^uE^uTNF^dD^d) congenic strains. Then, we compared amounts of TNF produced by peritoneal macrophages in vitro stimulated with LPS and INF_<gamma>, and serum TNF levels among these NZW,NZW.PL,NZW.H-2^d and NZW.H-2^b strains. The NZW strains showed much smaller amount of TNF production by macrophages and also lower level of serum TNF than another three NZW.PL,NZW.H-
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2^d and NZW.H-2^b strains of mice did. These results indicate that TNF gene polymorphism affects the TNF levels and that TNF^z is alow TNF haplotype, as compared with TNF^d of TNF^b haplotypes.
The development of antoimmune disease is tightly linked to the haplotype of mouse MHC,H-2. Based on our previous studies, we suggested that class II molecules, especially I-A,relate to this H-2 restriction. There was, however, the report that TNF gene linked to H-2 may be involved and that low TNF level of TNF^z haplotype of NZW mice is critical for the development of severe autoimmune disease in (NZB*NZW)F1 mice. We then investigated the relationship between TNF polymorphism and autoimmune disease, using established congenic strains. TNF production by perioneal macrophages and serum TNF level were much decreased in (NZB*NZW)F1 mice, because of TNF^z haplotype derived from NZW,as compared with (NZB*NZW.PL)F1 and (NZB*NZW.H-2^d)F1 mice. As for autoimmune disease, (NZB*NZW)F1 mice developed the most severe disease and (NZB*NZW.PL)F1 mice a little milder than (NZB*NZW)F1 mice. In contrast, the disease severity in (NZB*NZW.H-2^d)F1 mice was much reduced, as compared with another two F1 strains. (NZB*NZW.PL)F1 and (NZB*NZW.H-2^d)F1 mice have the same TNF haplotype and produce the same amount of TNF.The haplotypes of K,A and E regions of H-2 are differ between these two F1 strains. Thus, we concluded that haplotypes of K,A,and E,but not that of TNF,affect the autoimmune disease severity in these mouse strains. Less
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