Absence of CB2R expression on either CD4⁺or CD8⁺T cells exacerbates GVHD mortality. (A-G) Irradiated Balb/c mice received transplants of B6 Rag-1^−/− BM (5 × 10⁶; n = 7), Rag-1^−/− BM plus purified CD4⁺ (1 × 10⁶) and CD8⁺ (0.55 × 10⁶) B6 T cells (n = 10), Rag-1^−/− BM plus B6 CD4⁺ and CD8⁺ CB2R^−/− T cells (n = 10), and Rag-1^−/− BM plus CD4⁺ CB2R^−/− and B6 CD8⁺ T cells (n = 10). Overall survival is shown. Data are from 2 experiments. (B-C) Representative hematoxylin and eosin–stained sections of the lung, liver, and colon of animals 14 days posttransplantation are depicted in panel B. Original magnification is ×100 for photomicrographs. Pathological scores of colon, liver, and lung from mice undergoing transplantation are shown in panel C. Data are from 3 experiments, with 9 to 12 mice per group. (D-G) The absolute numbers of CD4⁺ and CD8⁺ T cells in the liver, lung, and colon are shown in panel D. The absolute numbers of CD8⁺ T cells that produced IFN-γ, granulocyte-macrophage colony-stimulating factor (GM-CSF), or tumor necrosis factor α (TNF-α) in the colon, liver, and lung 14 days posttransplantation are shown in panels E to G. Data are from 4 experiments, with 11 to 17 mice per group. *P < .05, **P < .01, ***P < .001, ****P < .0001.