IL-10 restores MHC class expression and interferes immunity in papillary thyroid cancer with Hashimoto's thyroiditis.

The incidence of papillary thyroid cancer (PTC) with concomitant Hashimoto's thyroiditis (HT) is increasing. Interleukin-10 (IL-10) is a cytokine previously reported to be elevated in this condition. Evidence from multiple human malignancies showed IL-10 participated in tumor immunity and exhibited therapeutic potential. The aim of this study is to investigate whether IL-10 interferes tumor immunity in PTC with concomitant HT. Expression of IL-10 and major histocompatibility complex (MHC) class were compared on PTC tissues with or without concomitant HT. PTC cell lines K1 and TPC-1 were stimulated with IL-10 and analyzed for MHC class expression afterwards. T cell activation, production of Interleukin-2 (IL-2) and IFN-gamma and programmed death-1 (PD-1) expression were assessed by coculture of donor peripheral blood lymphocytes (PBLs) with IL-10 pretreated PTC cells. Programmed death-ligand 1 (PD-L1) expression was measured in PTC tissues and IL-10 pretreated cells of K1 and TPC-1. Increased level of IL-10 and MHC class were observed in PTC with concomitant HT. IL-10 stimulation increased MHC class expression of PTC cells in vitro. Coculture of PBLs with IL-10 pretreated PTC cells enhanced T cell activation (%CD25+ of CD3+T cells) and increased IL-2 production along with decreased IFN-gamma secretion and PD-1 expression. Reduced PD-L1 expression was seen in PTC+HT tissue samples and IL-10 stimulated PTC cell lines. Elevated IL-10 expression in PTC with concomitant HT restores MHC class expression and interferes tumor immunity. The potential mechanism of IL-10 in tumor immunity needs further investigation.