Decreased absolute counts of T lymphocyte subsets and their relation to disease in squamous cell carcinoma of the head and neck

Abstract

Purpose: Apoptosis of circulating CD8+ T cells seen in patients with squamous cell carcinoma of the head and neck [SCCHN (Hoffmann T, et al. Clin Cancer Res 2002;8:2553-62)] suggested a possibility of lymphocyte imbalance. Therefore, absolute numbers and percentages of lymphocyte subsets were examined in the peripheral blood of SCCHN patients and controls.

Experimental design: Venous blood was obtained from 146 patients with SCCHN and 54 normal volunteers. Absolute numbers of CD3+, CD4+, and CD8+ T lymphocytes were determined using fluorobeads in a flow cytometry-based technique. Percentages of T lymphocyte subsets were also evaluated by flow cytometry. The patients were grouped at the time of blood draw [active versus no evidence of disease (NED), type of therapy administered, and the length of follow-up].

Results: Patients with SCCHN had significantly lower absolute numbers of CD3+ CD4+, and CD8+ T cells than normal controls. However, no differences in the percentages of T-cell subsets between patients and normal controls were observed. Patients with active disease had significantly lower CD3+ and CD4+ T-cell counts than those with NED. Patients who had NED after surgery and radiotherapy had the lowest T-cell counts among the NED cohort. Patients who had NED for >2 years did not recover their T-cell counts, and the T-cell imbalance was evident many years after curative surgery. The tumor-node-metastasis (TNM) stage or site of the disease was not related to the absolute T-cell count. Patients with recurrent disease at the time of blood draw tended to have the lowest CD4+ T-cell counts.

Conclusions: Patients with SCCHN have altered lymphocyte homeostasis, which persists for months or years after curative therapies.