Compared to conventional cardiac arrest post-resuscitation method, ECPR (VA-ECMO) increased spleen CD4+ T (helper) lymphocytes and CD4+/CD8+ T lymphocyte ratio, and enhanced T lymphocyte proliferation and low apoptotic rate. Paralleled by increased IL-2, IL-4 and IFN-γ levels and reduced ROS production in the spleen. All associated with increased survival. Here, CD4 is linked to cardiac arrest.