The IL-2 Defect in Systemic Lupus Erythematosus Disease Has an Expansive Effect on Host Immunity
Figure 2
IL-2 superfamily. IL-2, IL-15, and IL-21 are closely related in receptor binding, and function. IL-2 and IL-15 bind trimeric receptors and two of the three chains (IL-2, ) are the same, while each cytokine binds a unique third component of the receptor (IL-2or IL-15 respectively). The dimeric IL-21R consists of the chain, shared with IL-2R and IL-15R, and a unique chain, IL-21R. All three cytokines utilize the Janus kinases signaling molecules JAK1 and JAK3. IL-2 and IL-21 can activate STAT1/3/5 while IL-15 is only known to activate STAT5. While IL-2 and IL-21 can activate multiple STAT family members, IL-2 primarily signals through STAT5 homodimers whereas IL-21 mostly signals through STAT3 homodimers.
