Functional characterization of liver-associated lymphocytes in patients with liver metastasis

The liver-associated lymphocytes (LAL) population is mainly composed of cells with natural killer (NK) activity expressing the CD3+/-CD56+ phenotype. No evident difference has been found in the phenotypic data between patients with benign or malignant liver disease. In this study, the cytotoxic pattern of this population has been characterized from patients who underwent an operation for benign or metastatic liver disease.

LAL were isolated by sinusoidal high-pressure lavage from partial hepatectomies. Phenotype was characterized by flow cytometry, and cytotoxicity was evaluated by standard 4-hour 51Cr release assays against NK and lymphokine-activated killer (LAK)-sensitive targets.

In patients with benign liver disease, LAL showed spontaneous high levels of NK activity and LAK activity compared with peripheral blood lymphocytes. In patients with metastatic liver disease, no difference was observed in the levels of NK activity between LAL and peripheral blood, and the level of LAK activity was far lower than that expressed in patients with benign liver disease.

These results show that the cytotoxic pattern of peripheral blood lymphocytes does not mirror that of LAL. In patients with benign liver disease, LAL are in a state of activation, whereas the decreased level of LAL cytotoxicity in patients with metastatic liver disease suggests that the cytotoxic activity of these cells could be inhibited by the presence of suppressive factors.