Recipients of CD18^−/− donor T cells have significant less pathologic damage in intestine and liver. Lethally irradiated BALB/c mice were given intravenous injections of 5 × 10⁶ TCD BM cells alone or with naive T cells from WT or CD18^−/− B6 donors. On day 19, GVHD target organs, including liver, small intestine, colon, skin, and lung, were harvested for evaluation of histopathology as described in “Methods.” (A) Combined results of pathology scores for 5 to 6 mice in each group. Error bars indicate the standard errors of the mean in the group. (B) Representative micrographs from recipient livers and intestines of BM alone, WT, and CD18^−/− groups with original magnification ×600. Images were captured with an Olympus BX 40 microscope (Olympus, Melville, NY) equipped with a 10×/0.40 numerical aperture objective lens. Image acquisition was performed with a JVC GC-Qx 5HDU digital camera (JVC, Wayne, NJ). (C) Donor T-cell infiltration was determined by flow cytometry in liver and intestine. Left panels show the percentage of H2^b+ in total mononuclear cells isolated, and right panels show the percentage of CD4⁺ and CD8⁺ cells in gated H2^b+ cells. The data show average percentage of each cell population among 3 to 4 mice per group, and represent 1 of 3 replicate experiments.