Gas6 and Mer expression in aGVHD lesions of the large intestine and skin. (Aa-d) IHC of Gas6, Mer, Axl, and Tyro3 in the intestinal tissues of patients without aGVHD was performed. Analysis of the IHC results indicated that little to no expression of Gas6, Mer, Axl, or Tyro3 was observed in the large intestine of patients with negative histology for aGVHD. Scale bars represent 10 µm. Original magnification ×200. (Ba-b) CD3-positive infiltrating T lymphocytes were markedly increased in aGVHD lesions of the large intestine. Scale bars represent 10 µm. Original magnification ×200. (Bc-h) Gas6 and Mer were significantly upregulated in the aGVHD lesions of the large intestine, whereas little to no Axl or Tyro3 was detectable. Immunohistochemical stain for Gas6, Mer, Axl, or Tyro3. Arrows indicate Gas6 and Mer expression in aGVHD lesions of the large intestine. Scale bars represent 10 µm. Original magnification ×200. (Bi-k) Fluorescent IHC of Gas6 and Mer in aGVHD lesions of the large intestine was performed. Scale bars represent 10 µm. Original magnification ×200. (Bl) The statistical analysis revealed that the expression of Gas6 and Mer was increased in the aGVHD lesions of the large intestine compared with patients with no such lesions. We measured the intensity of Gas6 and Mer expression levels by color densitometry, using image J. Results are shown as mean ± SD of statistical analyses from 4 separate experiments. **P < .01, *P < .05. (Ca-d) IHC of Gas6, Mer, Axl, and Tyro3 in the aGVHD lesions of the skin was performed. Scale bars represent 50 µm. Original magnification ×200. (Ce-g) Fluorescent IHC of Gas6 and Mer in aGVHD lesions of the skin was performed. Scale bars represent 50 µm. Original magnification ×200.