Liver and spleen antiviral T-cell responses were significantly decreased in recipients with cGvHD. Lymphocytes harvested from the spleen and liver of recipients with and without cGvHD were stained with MCMV peptide–specific MHC class I tetramer, and tetramer-positive CD8⁺ T cells were measured by FACS analysis. Panels A and D represent the absolute number of donor spleen– (▪), donor BM– (□), and host-derived (▧) MCMV peptide–specific (HGIRNASFI-H2^b) tetramer-positive CD8⁺ T cells detected from the spleen and liver, respectively. Panels B, C and E, F represent the total frequency of donor spleen– and donor BM–derived intracellular IFN-γ– and TNF-α–producing CD8⁺ T cells per spleen and liver, respectively, on day 10 after MCMV infection as measured after 4 hours in vitro stimulation of total lymphocytes with HGIRNASFI MCMV peptide (□, cGvHD; ▪, no GvHD). *P < .05 and **P < .01 (Student t test) are for the decreased absolute numbers of MCMV peptide–specific tetramer-positive IFN-γ⁺ and TNF-α⁺ CD8⁺ T cells per organ in recipients with cGvHD compared with no GvHD.