Autoantibody in MRL/Mp-lpr/lpr mice. A monoclonal antibody specific for the abnormal T cells from mice bearing the lpr/lpr gene

We generated mAb from an unimmunized autoimmune MRL/Mp-lpr/lpr mouse. One of these mAb A108, reacted with cell surface Ag present on abnormal T cells from MRL/Mp-lpr/lpr, C3H-lpr/lpr, and C57BL/6-lpr/lpr mice. We failed to detect significant numbers of A108 bearing cells in the lymph nodes of MRL-Mp/+/+, normal C3H or normal C57BL/6 mice. Therefore, the expression of A108 correlates with the presence of the lpr/lpr gene. A108 binds to a variety of murine T cell tumor lines (e.g., EL4, BW5147, and YAC-1) and human T cell tumor lines (e.g., MOLT-3, Sup T1, and Jurkat). A108 does not bind to normal human PBL. Immunoprecipitation of surface iodinated EL-4 and BW5147 with A108 identified one major protein with a Mr of about 17.5-kDa. The significance of these findings with respect to the development of lymphoid proliferation and autoimmune disease in mice bearing the lpr/lpr gene will be discussed.