The toransujienitsuku non human mammal which reproduces the sick condition of human joint riumachi satisfactorily is offered. The mutant of the B7.1 gene, and the B7.1 gene (however, in regard to the activation of the T cell, has the function which is equal to the B7.1 gene) from the group which consists of the DNA arrangement which is selected under controlling II type collagen promoter being arranged, the imported characteristic DNA which becomes, is introduced into the occurrence early cell, the toransujienitsuku non human mammal is obtained.ヒト関節リウマチの病態を良好に再現するトランスジェニック非ヒト哺乳動物を提供する。B7.1遺伝子、及びB7.1遺伝子の変異体(但し、T細胞の活性化に関してB7.1遺伝子と同等の機能を有する)からなる群より選択されるDNA配列がII型コラーゲンプロモーターの制御下に配置されてなる外来性DNAを、発生初期の細胞に導入し、トランスジェニック非ヒト哺乳動物を得る。
