BACKGROUNDCytotoxic lymphocytes play an important role in anti-tumor immune. CD₃+CD₅₆+NKT cells, which are a new type of cytotoxic cells, are mainly focused on anti-tumor effect in hematologic malignancy, however its cytotoxic effects on solid tumor are not clear. The aim of this study is to explore the clinical expression and significance of peripheral CD₃+CD₅₆+NKT cells and CD₃-CD₅₆+NK cells in patients with solid malignant tumors.

METHODSPeripheral T cell subsets and CD₃+CD₅₆+NKT cells and CD₃-CD₅₆+NK cells in 118 patients with malignant tumors (55 lung cancers and 63 breast cancers) and 46 healthy volunteers were analysed by flow cytometer.

RESULTSCompared with healthy control, both peripheral CD₃+T lymphocytes and CD₃+CD₄+ T lymphocytes in patients with lung cancer or breast cancer significantly decreased, but CD₃+CD₈+T lymphocytes only increased significantly in patients with lung cancer (P < 0.01). Further analysis of CD₃+CD₅₆+NKT cells and CD₃-CD₅₆+NK cells indicated that there was difference between lung cancer group and breast cancer group. In patients with lung cancer CD₃+CD₈+T cells and CD₃+CD₅₆+NKT cells increased significantly, and in patients with breast cancer CD₃+CD₅₆+NKT cells and CD₃-CD₅₆+NK cells increased obviously.

CONCLUSIONSIn patients with lung cancer or breast cancer, CD₃+CD₅₆+NKT cells play the important role in anti-tumor effects, however, the anti-tumor effects of CD₃+CD₈+CTL and CD₃-CD₅₆+ NK cells were different.