In the Scl-cGVHD model, immunodominant and pathogenic alloreactive Vβ3⁺T cells expand rapidly post-transplant and their elimination mitigates Scl-cGVHD. BALB/c mice were lethally irradiated and transplanted with B10.D2-Thy1.2 TCD BM (10⁷ cells) supplemented with 12 × 10⁶ CFSE-labeled B10.D2-Thy1.1 WT splenocytes. (A) Expression of Vβ3 in donor-derived CD90.1⁺CD4⁺ T cells in spleen or lymph nodes at the indicated time points after transplant. Vβ3⁺ T cells proliferated and expanded rapidly to become the majority of donor T cells on day 6, before their subsequent contraction. Representative flow cytometry plots, with numbers indicating the percentage of Vβ3⁺ cells among donor-derived CD4⁺ T cells (left). (B-C) B10.D2→BALB/c chimeras were generated by transplanting TCD BM only (light green circle) vs TCD BM with 3 × 10⁶ WT T cells depleted of Vβ3⁺ T cells (blue circle) or sham manipulated (red circle). (B) Cutaneous cGVHD manifestations were monitored biweekly. Note significant cutaneous GVHD score reduction in mice receiving Vβ3-depleted T cells as compared with whole T-cell recipients. *P < .05 for all comparisons (1-way ANOVA). (C-D) Histopathologic analysis of animals depicted in panel (B). (C-D) Cumulative data show decreased pathological hallmarks of cGVHD (C) with transplantation of Vβ3-depleted T cells, without corresponding impact on the severity of aGVHD (D). *P < .05 (1-way ANOVA). (E) Representative microphotographs of hematoxylin and eosin–stained skin sections showing increased dermal thickness in the whole T cell as compared with TCD BM recipients, with decreased thickness in recipients of Vβ3-depleted T cells (ear lobes, day 60). Scale bar represents 100 µm.