ABSTRACT
Objective To investigate the different distribution of regulatory T cells (Tregs) and CD8+T cells in the local immune microenvironment of mucosal malignant melanoma and cutaneous malignant melanoma, and analyze the relationship between the two indicators and the prognosis of patients. Methods Immunohistochemistry staining was used to assess the ex?pression of Foxp3+Tregs and CD8+T cells in tumor microenvironment of 58 patients with malignant melanoma. The correlation between two factors, clinicopathological characteristics, and prognosis were analyzed. Results There is no correlation be?tween the expression of Foxp3 and CD8. The number of Foxp3+Tregs was significantly higher in mucosa malignant melanoma than that in cutaneous malignant melanoma (t=2.648, P=0.011). The proportion of Foxp3highTregs was significantly higher in pa?tients with tumor diameter≥3 cm, lymph node metastasis and distant metastasis than that in patients with tumor diameter<3 cm, no lymph node metastasis and no distant metastasis (P<0.05). In addition, in patients with ulceration that proportion was significantly higher in CD8high group than that in patients without ulceration (33.3%vs 5.9%, P<0.05). The median progres?sion-free surial (PFS) was 12 months in Foxp3high group, which was significantly longer than that of Foxp3low group (31 months, P<0.05). The median PFS was significantly higher in CD8high group (25 months) than that of CD8low group (12 months, P<0.05). Subgroup analysis showed that the median PFS was 7 months in Foxp3high CD8low group, which was significantly lower than that of Foxp3highCD8high group (25 months) and Foxp3lowCD8low group (18 months, P=0.003). Univariate analysis showed that median PFS was different in patients with different tumor location, different number of Foxp3+Treg, different number of CD8+T cells, and distant metastases. Conclusion The number of Tregs is closely associated with metastasis in patients with malig?nant melanoma. Compared with cutaneous malignant melanoma, our results indicate that the poor prognosis of mucosal malig?nant melanoma may be associated with the infiltration of more Tregs.