Self Reactive Repertoire of Tight Skin Mouse: Immunochemical and Molecular Characterization of Anti-Topoisomerase I Autoantibodies

Tight skin (TSK) mice develop cutaneous hyperplasia accompanied by histopathological alterations of skin and collagen metabolism similar to those described in human scleroderma. Diffuse scleroderma, the most severe form of progressive systemic sclerosis, is associated with the production of autoantibodies specific for Scleroderma 70 antigen (topoisomerase I). Our studies show that there is an increase in the level of serum anti-topoisomerase I (topo I) autoantibodies in aged TSK mice. The monoclonal antibodies isolated from TSK mice bind to epitopes which interact with autoantibodies from scleroderma patients. A significant number of TSK monoclonal anti-topo I antibodies and serum immunoglobulin (Ig) from aged TSK mice bear a cross reactive idiotype (Id) recognized by a syngeneic monoclonal anti-Id antibody obtained from a 2 month-old TSK mouse. Analysis of V gene usage by monoclonal anti-topo I antibodies showed that the majority of these antibodies are encoded by VH genes derived from VHJ558 family pairing with VK genes from various families in a stochastic manner.