CD4 and congenital rubella syndrome: With respect to the CAR-T, the mean frequencies of CD8+ and CD4+ CAR-T in the mild CRS group were respectively 59% (0.46 × 106/kg) and 41% (0.25 × 106/kg), and those in the severe group were respectively 62% (0.43 × 106/kg) and 38% (0.32 × 106/kg).