Within the samples containing detectable levels of the three ligands, no obvious differences were seen between the mean values of BLyS, APRIL, or heterotrimers levels in healthy donors compared with the mean values of each ligand in patients with SLE or RA, with the possible exception of elevated APRIL levels in patients with RA (Table 1). Here, TNFSF13B is linked to systemic lupus erythematosus.