IgM was undetectable in both the SLE and healthy controls, including the IgG(1–19low91low)IgM(1–19high91high), IgG(1–19low91low)IgM(1–19high91low) and IgG(1–19high91x)IgM(1–19x91x) subgroups, indicating that the high IgM reactivity in Figure 1 was due to low- or non-specific binding. This evidence concerns the gene CD40LG and systemic lupus erythematosus.