HPX and systemic lupus erythematosus: Nevertheless, the remaining candidate serum proteins consisting of serotransferrin, tumor necrosis factor receptor type II, fibrinogen beta chain, hemopexin, alpha-1-acid glycoprotein 2, tyrosine-protein kinase receptor UFO, and protein S100-A9 were found to not be associated with all of the circulatory molecules related to SLE severity in this study (CRP, complement C3 and C4) (Fig. 3).