FAS and Lymphadenopathy: However, B6 mice deficient for Fas (CD95) develop a mild lupus-like disease characterized by lymphadenopathy, splenomegaly and production of increased titers of IgG antibodies to a variety of auto-antigens including DNA, anti-nuclear antigens (ANA), and the Fc portion of autologous IgG (Cohen and Eisenberg, 1991; Izui et al., 1984).