Elevated levels of IL-2 (a Th1 cytokine) and reduced levels of MCP-1 (a Th2 chemokine) in the ICI-TD group indicate an increase in the Th1/Th2 balance,[33] consistent with the Th1 imbalance observed in HT.[49] CD8+ T cells activated by IL-2 may destroy immune tolerance, targeting not only tumor cells but also attacking thyroid cells, leading to ICI-TD. This evidence concerns the gene IL2 and hematocrit.