IL21 and lipoprotein glomerulopathy: Three signals are associated with T cell activation: signal 1 “antigenic stimulation,” signal 2 “co-stimulatory signals through CD28 or 4-1BB,” and signal 3 “cytokines of IL-12, IL-21 or IFN-alpha.” In the current study, representative T-cell co-signal molecules of the CD28-B7, TNFSF/TNFRSF, and TRAF families (32, 33) were upregulated in the LPG group, as were survival-related cytokine genes (IL-2R, IL-7R, IL-15R, and STAT1/3/5) were up-regulated LPG group in this study.