IL17A and graft versus host disease: To better elucidate the mechanism of the CD27-CD70 pathway and its impact on GVHD pathogenesis, cytokines associated with GVHD were measured in CD70 knockout host mice which showed significantly higher levels of pro-inflammatory IFNγ, TNFα, IL-2, and IL-17 when compared to WT mice (see Figure 3) (35).