Yang et al raise concerns about our method of quantifying Treg numbers. We used three well-cited methods: CD4 + FoxP3 + , CD4 + CD25bright + and CD4 + CD25 + CD127 − . There is no consensus regarding the best method of measuring Treg numbers, so we took a comprehensive approach. Although Yang et al favor CD4 + CD25 + FOXP3 for quantifying Tregs, it should be noted that many scientists agree that CD4 + FoxP3 + expression is of key importance, as we described previously. We have plotted the data using CD4 + CD25 + FOXP3 (Fig 1), which gives a similar pattern to the analysis using CD4 + FOXP3 (healthy vs moderate/severe, P = .003). Either approach appears valid for identifying Tregs in the airways.