CD4 and Omenn syndrome: Membrane bound CD30-CD30L signaling promotes the activation of NF-κB and the production of Th2 type cytokines from CD4+ and CD8+ T cells [85]; however, increased production of sCD30 leads to an over-activation of this pathway and has been linked to several Th2 mediated diseases including systemic lupus erythematosus, rheumatoid arthritis, atopic dermatitis, and Omenn’s syndrome [84–86].