CD4 and chronic lung allograft dysfunction: Similar results were also observed in clinical data, which showed that increased frequencies of FoxP3+CD4+CD25+ Tregs 3 weeks after lung transplantation were associated with a reduced chance of chronic lung allograft dysfunction at 2 years22, suggesting that immediate expansion of FoxP3+CD4+CD25+ Tregs post transplantation may exert a protective effect on the long-term survival of the grafts.