Figure 1. Representative specimens showing low and high expression of HO-1 and CD163 in nasopharyngeal carcinoma tissues. Immunohistochemical staining of HO-1 and CD163 are presented. HO-1 and CD163 immunohistochemical scoring: score 0 (no staining), score 1 (weak staining), score 2 (moderate staining), score 3 (strong staining). Staining intensities with scores no greater than 1 were defined as low expression while as high expression when scores are above 1. (A) low expression of HO-1. (B) high expression of HO-1. (C) low expression of CD163. (D) high expression of CD163. (B, D) are from the same section view of tumor specimen of the same patient. Arrows point out co-expression of HO-1 and CD163 in tumor-associated macrophages (TAMs). Scale bar, 50 μm. Magnification, 20×.