1. CTLA-4 and PD-1 modulate different aspects of the T-cell response: A, CTLA-4 is upregulated after antigen-specific activation of a naïve or memory T cell in lymphatic tissue, leading to decreased effector function (early activation phase).
CTLA-4 and PD-1 modulate different aspects of the T-cell response: A, CTLA-4 is upregulated after antigen-specific activation of a naïve or memory T cell in lymphatic tissue, leading to decreased effector function (early activation phase). B, PD-1 is mainly expressed on antigen-experienced memory T cells in peripheral tissues cells. The immune modulation mediated by this pathway ensures protection of tissue from collateral damage during an inflammatory response. Tumor cells use this regulatory mechanism to evade a tumor-directed T-cell response by upregulating the PD-1 ligands B7-H1 and B7-DC.
Patrick A. Ott et al. Clin Cancer Res 2013;19:
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