Interestingly, in the context of lung transplantation, Greenland et al reported a significant increased proportion of CD4+CD25+ Tregs in the BAL of patients with the acute rejection of Grade > A1 who will develop BOS (50) suggesting that this increase in Tregs could also be found in the target graft long before BOS development. Here, CD4 is linked to Buschke-Ollendorff syndrome.