PTPRC and Splenomegaly: As the Faslpr/lpr mutation allows the expansion, in SLOs, of CD3 + B220 + auto-reactive T cells deriving from precursors unable of apoptosis in the thymus [29], we evaluated the percentage of this population as a parameter of the autoimmune severity and found a higher expansion of CD3 + B220 + cells in Faslpr/lpr than OPN-/-Faslpr/lpr spleens (Fig. S1B), associated with exacerbated splenomegaly (Fig. S1C).