Increased numbers but functional defects of CD56+CD3+ cells in lung cancer

CD56+ T cells were studied in samples of peripheral blood from small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC) patients compared with healthy controls. Relative numbers of CD56+CD3+ cells were increased in NSCLC (P = 0.001) and SCLC (P = 0.002) compared with normal subjects but their ability to respond to activation by up-regulating CD25 or producing IFN-gamma were both significantly impaired. Expression of the killer-immunoglobulin-like receptor CD158a was significantly lower on CD56+CD3+ cells in SCLC than controls and also in early stage compared with late stage NSCLC patients. Mean levels of CD158e were higher in NSCLC patients than controls. CD158e levels on CD56+CD3+ cells were increased in the presence of its ligand HLA-Bw4 compared with controls. Although the precise role of CD56+CD3+ cells is not clear, they appear to be functionally impaired in lung cancer, which may have implications for a reduction of direct or indirect anti-tumour responses.