CD4 and graft versus host disease: The main cells involved in GvL are effector lymphocytes such as NK-cells, CD8+ T-cells, and γδ T-cells (74–76); whereas the main cells involved in GvHD are naïve CD4+ and CD8+ T-cells, total CD4+ T-cells, B-cells and potentially central memory (CM) CD4+ T-cells (76–79).