Tumour necrosis factor α impairs function of liver derived T lymphocytes and natural killer cells in patients with primary sclerosing cholangitis

BACKGROUND—Primary sclerosing cholangitis (PSC) is considered to be a chronic autoimmune disease where infiltrating T lymphocytes have been implicated in the destruction of bile ducts. Altered function of these T cells may reflect abnormalities in the immune response leading to tissue damage.
AIM—We investigated the proliferative and functional capacity of freshly isolated liver derived T lymphocytes (LDLs) and natural killer (NK) cells from PSC patients.
METHODS—The proliferative responses to common mitogens such as phytohaemagglutinin (PHA), concanavalin A (Con A), and lipopolysaccharide (LPS) were studied, and the cytotoxic function of T lymphocytes was measured using allogeneic target cells. NK (CD56(+)/16(+)) cytotoxic function was measured using the two cell lines K562 (NK sensitive) and Raji lymphoma cells (NK resistant).
RESULTS—Compared with patients with primary biliary cirrhosis (PBC), autoimmune hepatitis (AIH), and normal controls (without liver disease), in PSC: (1) LDLs contained a low percentage of T cells; (2) there was significantly decreased expression of interleukin (IL)-2 receptor (p<0.001) on activated T cells (HLA-DR(+)); (3) LDLs but not peripheral blood lymphocytes had significantly impaired proliferative responses to mitogens such as PHA, Con A, and LPS (p< 0.001); (4) no cytotoxic activity of PSC liver T and NK cells was recorded; (5) significantly higher levels of tumour necrosis factor α (TNF-α) and IL-1β but lower levels of IL-2, IL-10, and interferon γ were found in the supernatants of mitogen stimulated LDL cultures (p<0.001); (6) higher percentages of freshly isolated PSC LDLs contained intracytoplasmic TNF-α and IL-1β; and (7) pretreatment of PSC LDLs in vitro with neutralising TNF antibodies significantly enhanced proliferative responses and allowed IL-2 receptor expression following stimulation. In addition, the impaired cytolytic activity of both NK and T cells was partially restored. Impaired proliferative or functional capacity of liver derived T cells was not observed in either PBC or AIH patients.
CONCLUSIONS—We suggest that reduced T cell reactivity in liver infiltrating cells obtained from patients with PSC is due to high local production of TNF-α. Our findings indicate that the use of anti-TNF antibodies as an alternative treatment for PSC patients should be evaluated.


Keywords: autoimmune liver diseases; biliary epithelial cells; cytokine