KGF treatment preserves the thymic microenvironment during acute GVHD.

GVHD was induced in KGF- or HBSS-treated B6D2F₁ mice, as described in Figure 1, and mice were analyzed on day 13 after transplantation. HBSS-treated B6D2F₁ mice that received syngeneic transplants served as non-GVHD controls. (A) Frozen thymic sections (6 μm) from the 3 transplant groups were analyzed for histopathology (Hematoxylin + Eosin stain; original magnification × 200). (B) Immunohistology of 4 distinct subpopulations of thymic epithelial cells in mice that received allogeneic and syngeneic transplants. Thymic epithelial cells were identified using a panel of antibodies according to Table 1. Two-color immunoflourescent analyses were performed using a confocal microscope (Carl-Zeiss). Major cortical cells appear blue (i-iii), whereas minor cortical TEC (iv-vi), major medullary TEC (vii-ix), and minor medullary TEC appear white (x-xii) (ie, altered color by computer-assisted management of confocal microscopy data, see Table 1). The arrows denote individual positive cells. Original magnification × 200. The data substantiate that KGF treatment preserves in the presence of GVHD the normal structure of cortical and major medullary TECs but not of the subpopulation of minor medullary TECs. C indicates cortex; M, medulla.