A high number of CD8+ T cells infiltrated in NSCLC tissues is associated with a favorable prognosis.

We investigated the number of intratumoral tumor-infiltrating lymphocytes (TILs), including CD4(+), CD8(+), and CD25(+) T cells, in nonsmall cell lung cancers (NSCLC) and their correlation with patient survival time. Tumor specimens from 30 NSCLC patients were consecutively obtained during surgery. Patient survival status was monitored. Based on survival time, patients were divided into 2 groups: 5-year survival group and 5-year nonsurvival group. CD4(+), CD8(+), and CD25(+) T cells that infiltrated tumors were detected and counted by immunohistochemistry. Patients with a lower number of TILs and CD8(+) T cells showed significantly shorter survival time compared with those with a higher number (P < 0.05). However, the number of CD4(+) and CD25(+) T cells in tumors was not correlated with survival time in patients with NSCLC (P > 0.05). These data demonstrate that high numbers of CD8(+) T cells among TILs is a strong indicator for a favorable clinical outcome.