2.4. Transient IFN-γ Responses but Reduced Inflammatory Cytokine Responses by Lymph Node Cells from PD-1 Antibody-Treated Lesion-Bearing Mice to a Challenge of Tongue Premalignant Lesion and Head and Neck Squamous Cell Carcinoma Lysates. This evidence concerns the gene PDCD1 and head and neck squamous cell carcinoma.