Histopathology and immunohistochemistry of intestine.

Tissue was prepared as described in “Materials and methods.” For immunohistochemistry, sections were stained with biotin-labeled rat monoclonal antibodies to either CD4 or CD8, followed by streptavidin-conjugated horseradish peroxidase and development with 3-AEC. Sections were counterstained with hematoxylin. Note on H&E-stained sections the massive inflammatory infiltration and isolated apoptotic cells in the IL-4-tk splenocyte recipient treated with PBS, which had GVHD. IL-4-tk splenocyte recipients treated with GCV and BM controls appeared normal. Immunohistochemistry revealed many more CD4⁺ and CD8⁺ cells in the IL-4-tk splenocyte recipient treated with PBS compared with a similar mouse treated with GCV or that received BM alone. Apparent magnification × 250.