IL-2 group had lower incidence of infection than non-IL-2 group in upper respiratory tract infection (4.6%,10/219 v.s. 13.9%, 62/446, P-value < 0.001) and to herpes zoster infection (0%, 0/219 v.s. 2.9%, 13/446, P-value = 0.007) (Table 2). This evidence concerns the gene IL2 and infection.