The candidate serum/plasma proteins, which were found in only SLE patients, consisted of tumor necrosis factor receptor type II (TNFR2), tyrosine-protein kinase receptor UFO (Axl ), hemopexin (HPX ), fibrinogen beta chain (FGB), and serotransferrin (TF ) (Fig. 1). Here, HPX is linked to systemic lupus erythematosus.