Lymphocyte-deficient (RAG2^-/-) recipients have accelerated cGVHD with greater penetrance and severity. Combined data from 3 experiments. On day 0, recipient mice were lethally irradiated and reconstituted with 8 × 10⁶ B10.D2 BM cells alone (n = 19, all recipient types) or BM plus B10.D2 10⁷ spleen cells: WT (n = 32), RAG2^-/- (n = 28). In a separate experiment, RAG2^-/- recipient mice were lethally irradiated and reconstituted with 8 × 10⁶ syngeneic (BALB/c) BM plus 10⁷ syngeneic (BALB/c) spleen cells (n = 9). (A) Incidence of cGVHD. †P < .01 for RAG2^-/- recipients compared with WT recipients. (B) Average clinical disease score for mice affected with cGVHD (unaffected mice are excluded). ^*P < .05, †P < .01 for RAG2^-/- recipients compared with WT recipients. BM control mice and RAG2^-/- recipients of syngeneic cells did not get cGVHD and are represented on the graph as scoring “0.” (C) Pathology score for representative mice. Mean score is indicated by a horizontal bar. ^*P < .05 for RAG2^-/- recipients compared with WT recipients. Pathology samples were taken on day 24, 33, or 50.