IL15 and Decreased total leukocyte count: CTX also results in profound leukopenia; however, adoptive cell therapy post CTX treatment suggests transplanted cells are able to exploit the present immune milieu of type I interferons and cytokines (IFN-γ, IL-1β, IL-2, IL-7, IL-15, and IL-21), and promote both B- and T-lymphocyte homeostatic proliferation and activation with a predominately Th17 signature49,52.