Time elapsed after transplantation influences the relationship between the number of regulatory T cells in lung allograft biopsies and subsequent acute rejection episodes.

•We assessed the number of Tregs in lung allograft biopsies at several time points.•These results were compared to the degree of acute rejection (ACR).•Previous levels of Tregs/mm2 did not have any effect on future levels of Tregs/mm2.•Tregs/mm2 and the degree of ACR were correlated only at the early time points.•Time elapsed after transplantation is a parameter influencing the Treg response.