Depletion of CD25-expressing cells from Tgf-β1^-/- spleen cells accelerated lymphocyte expansion and inflammation in Rag2^-/- recipients. Whole splenocytes or CD25-depleted splenocytes (1 × 10⁷ cells/mouse) from Tgf-β1^+/+ or Tgf-β1^-/- donor mice were transferred into Rag2^-/- recipient mice. (A) H&E-stained sections of heart and CD3 immunostained sections of liver and lung of Rag2^-/- recipients of whole or CD25-depleted splenocytes are shown. Original magnification, × 100. (B) BrdU-positive CD4⁺ and CD8⁺ cells in spleens from the recipients are shown. One representative result from 5 separate analyses is shown.