CD40LG and systemic lupus erythematosus: In two studies using SLE prone mouse strains (MRL-lpr/lpr) and NZB x NZW that spontaneously develop SLE (characterized by severe immune complex-mediated glomerulonephritis and death by 12 months of age from renal failure), secreted IgM (sIgM) was shown to be essential in preventing disease (Table 1) (137, 138).