CD4 and graft versus host disease: Further, the data does not yet fully address the impact of specific iNKT subsets on relapse rates, as murine studies show that CD4+ iNKT cell-mediated GVHD suppression does not result in loss of GVL, while both murine and human preclinical studies suggest malignant cell killing function lies with CD4-/iNKT1 which could potentially allow for synergy with T cell-mediated malignant cell killing (11, 44).