Therapeutic efficacy of anti-GARP:TGF-β1 mAb in murine PMF requires T cell function. (A) Recipient mice were transplanted with transformed MPL^W508A/GFP⁺ cells and injected IP weekly with 58A2 and/or anti-CD8α mAbs at the time points indicated. Blood samples were collected weekly starting on day 14 for blood cell count and flow cytometry. Mice were euthanized on day 35. (B) Counts of GFP⁺ blood neutrophiles during PMF progression. Data points: mean values per group (n = 6-8 mice per group). P values were calculated with a repeated measure analysis of variance.