Dominant clonotypes are present in colitis mediated through the indirect alloreactive pathway. (A) Lethally irradiated (900 cGy) Balb/c Rag mice (n = 4) were transplanted with 10 × 10⁶ BM cells from B6 Rag animals. Representative dot plot showing the percentage of CD11c⁺ cells that were donor-derived (H-2K^b+) in specified tissue sites 80 days after transplantation is shown. (B) Lethally irradiated Balb/c mice were transplanted with B6 BM and 0.4 × 10⁶ spleen cells. Animals were then euthanized 24-25 days after transplantation. Spleen cells (adjusted to yield a T-cell dose of 0.5 × 10⁶) were pooled from mice and infused intravenously into nonirradiated B6 Rag BM → Balb Rag chimeric mice that had been reconstituted 60-70 days earlier. Serial weight curve and pathologic damage in the colon (n = 9) using a semiquantitative scoring system is depicted. Data represent cumulative results from 2 experiments. Histology of colon from a representative animal shows extensive inflammation in the lamina propria and loss of mucin. Magnification is 20× for the top panel and 100× for the bottom panel. (C-D) Chimeric B6 Rag BM → Balb/c Rag mice were adoptively transferred with pooled spleen cells from primary GVHD B6 → Balb/c animals (n = 10). Mice were killed 60-70 days after transfer and TCRβ spectratype and clonotype analysis were performed on processed colon tissue. The name and number of CDR3 region amino acid sequences derived from dominant peaks in specified Vβ families is depicted. Colors in bar graphs represent individual mice. Panels C and D are results from 2 independent experiments with 4-5 animals per experiment. (E) Table denoting the total number of sequences and clonotypes derived from colons of mice in experiments detailed in panels C and D.