Renal damage and donor T-cell infiltration are increased in allo-HCT recipients. BALB/c (H-2^d) animals were lethally irradiated and received transplantation with CD90.2⁺ splenic T cells together with BM cells from either syn BALB/c or allo MHC-mismatched B6 (H-2^b) donors. The kidneys were collected from recipient mice on day 14 after HCT. (A) Representative images of PAS-stained kidneys after HCT are shown. Compared with the syn group, there was increased mononuclear cell infiltration in the peritubular capillaries (PTCs; see arrows in center bottom row image) and tubules (see arrows in right bottom row image) of allogeneic recipients. (B) Quantification of infiltrating mononuclear cells (MNCs) in kidneys is shown. The number of infiltrating MNCs per 200× original magnification field is significantly higher in allo mice than in syn mice. (C) Representative H-2K^b (green) and 4′,6-diamidino-2-phenylindole (DAPI; blue) immunofluorescence images are shown. H-2K^b–positive donor-derived cells were found in the kidneys of allogeneic recipients. (D) Representative images of immunohistological staining for CD3 are shown. Allogeneic recipients demonstrated increased CD3⁺ T-cell infiltration in the peritubular, perivascular, and glomerular areas relative to syngeneic recipients. (E-G) Quantification of T cells infiltrating the kidneys is shown. The absolute number of CD3⁺ T cells infiltrating the glomeruli (E), interstitium (F), and perivascular area (G) was significantly higher in allogeneic mice than in syngeneic mice; n = 3 to 5 mice per group. Data shown represent 2 experiments. Magnifications are shown in the figures. The bars represent the mean ± SEM. Student t test was used for statistical analysis; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001 for panels B,E-G.