Significant increases in ANA and rheumatoid factor titres have been found in B6lpr and MRLlpr mice in the absence of CR2 but these have little negative effect with respect to renal function (Boackle et al., 2004; Wu et al., 2002) and suggests that whilst CR2 is highly important with respect to the type, level and specificity of auto-antibodies generated in the absence of Fas, it does not dramatically alter the outcome of this autoimmune disease model. Here, FAS is linked to autoimmune disease.