Tumor metastases to regional lymph nodes are associated with worse outcome for patients with resected non-small cell lung cancer (NSCLC), but there is a wide variation in survival. We hypothesized that infiltration of tumor-involved lymph nodes with activated effector T cells would impact subsequent outcome. A total of 54 lymph nodes (27 N(+) and 15 N(-) collected from 12 patients with Stage IIB (T(2)N(1)M(0)) and 12 N(-) lymph nodes collected from 10 patients with Stage IIA (T(2)N(0)M(0)) who underwent lymphadenectomy during surgical management of their NSCLC) were analyzed for effector T cells expressing activation markers PD-1 and TIM-3 using the Opal-multiple immunofluorescence assay. The frequency of CD3(+)CD8(+) (P=0.0001), CD3(+)CD8(+)TIM-3(+) (P