Evaluation of circulating Tregs and mMDSC immune-regulatory subsets in patients with MDS-SR at baseline and after 24 weeks of luspatercept treatment. Purple, blue, and red columns indicate data obtained from healthy CTRs and from patients with MDS-SR before (T0) and after 24 weeks of luspatercept treatment (T1). The expression of the Foxp3-Ex2 transcription factor indicates highly effective Tregs (see text for details). (A-B) Percentage of circulating Tregs expressing Foxp3⁺ and Foxp3-Ex2⁺. (C-D) Number of circulating Tregs expressing Foxp3⁺ and Foxp3-Ex2⁺. (E) The Foxp3-Ex2/Foxp3 ratio. (F) Percentage of circulating mMDSCs. (G) Scatterplot analysis showing correlation between the frequencies of Foxp3-expressing Tregs and circulating mMDSCs in patients with MDS-SR at T1. (H) Scatterplot showing the correlation between the frequency of circulating Foxp3-Ex2⁺CD4⁺ Tregs and mMDSCs at T1. (I) Scatterplot showing the correlation between the frequencies of circulating Ki67⁺Foxp3-Ex2⁺CD4⁺ Tregs and mMDSCs at T1. For statistical evaluation details, see supplemental Materials.