BACKGROUND.
T helper type 1 cells (Th1), Th2, T cytotoxic type 1 cells (Tc1), and Tc2 play important immunoregulatory roles. Some recent studies have demonstrated that an elevated level of type 2 cytokines, such as interleukin-10, contributes to the ability of cancer cells to escape immunosurveillance. However, the impacts of Th1, Th2, Tc1, and Tc2 on tumor immunity are unclear.
METHODS.
The authors evaluated the ratio of Th1 to Th2 and that of Tc1 to Tc2 among peripheral blood lymphocytes (PBL), regional lymph node lymphocytes (RLNL), and tumor-infiltrating lymphocytes (TIL) in 46 nonsmall cell lung carcinoma patients who had just undergone surgery; the evaluation involved detecting the intracellular interferon-β₯ and interleukin-4 production with 3-color flow cytometry. They also evaluated the same ratios in the peripheral blood lymphocytes of 29 lung carcinoma patients with or without recurrence after surgery, and in the peripheral blood of normal volunteers.
RESULTS.
The Th1-to-Th2 and Tc1-to-Tc2 ratios were significantly elevated in the tumor tissues. These ratios in the TIL were significantly elevated in the groups of patients with squamous cell carcinoma and a history of smoking. The Th1-to-Th2 and Tc1-to-Tc2 ratios were significantly depressed in the PBL of the patients with tumor recurrences.
CONCLUSIONS.
A favorable Th1-and Tc1-dominant pathway is induced in the tumor tissues of operable patients, but their pathway can be expected to shift from Th1 or Tc1 to Th2 or Tc2 with the progression of cancer.