The upregulation of signaling through negative co-stimulatory molecules on T cells, such as Cytotoxic T-lymphocyte Antigen 4 (CTLA-4) and programmed cell death-1 (PD-1), is another mechanism through which T-cell infiltration and function can be impaired in cervical cancer.16,17. This evidence concerns the gene PDCD1 and cervical carcinoma.