The Distribution of M2 Macrophage and Treg in Nasopharyngeal Carcinoma Tumor Tissue and the Correlation with TNM Status and Clinical Stage

Objective: This study aimed to identify the distribution of M2 macrophage and Treg in Nasopharyngeal Carcinoma
(NPC) tumor tissue samples. The presence of these two groups of cells was further correlated to clinical stage, tumor
size, the lymphatic node involvement, and metastasis.

Methods: The total of 50 formalin-fixed paraffin-embedded
(FFPE) NPC tissue samples was collected retrospectively (27 samples) and prospectively (23 samples). Samples were
FFPE tissue slices. Immunohistochemistry was done on the FFPE tissue slides using anti-CD-163 and anti-FoxP-3
antibodies for M2 macrophage and Treg detection, respectively. The M2 macrophage interpretation was performed
by eye-balling method and the score was divided into 0 (negative), 1 (scant), 2 (focal), and 3 (abundant). The average number of Treg FOXP3+ cells in 5 high power fields (HPF) was calculated. The relationship of M2 macrophage and
Treg was tested with Spearman’s correlation. The relationship between M2 macrophage and Treg with clinical stage, tumor size, node involvement and metastasis was tested by chi square, with p<0.1.

Results: M2 macrophage and Treg were positive correlated (r=0.469, p<0.001). The presence of M2 macrophage and regulatory T cell (Treg) was significantly correlated to tumor size (p= 0.091 for M2 macrophage and p=0.022 for Treg) and clinical stage (p= 0.030 for M2 macrophage and p= 0.002 for Treg), but did not correlate with lymphatic node involvement and metastasis.

Conclusions: In Epstein-Barr virus related NPC tumor microenvironment, the presence of M2 macrophage was
correlated with Treg, and both types of the cells were correlated with tumor size and clinical stages.