α-Fetoprotein impairs activation of natural killer cells by inhibiting the function of dendritic cells.

α-Fetoprotein (AFP) is a tumour-associated antigen in hepatocellular carcinoma (HCC). The biological properties of AFP have been identified in its regulatory effects on immune responses of T cells and B cells. However, AFP effects on natural killer (NK) cells are still unclear. In this study, we examined the immunoregulation of AFP on NK activity. The cytolytic activity against K562 cells and Huh7 cells of NK cells co-cultured with AFP-treated dendritic cells (DCs) (AFP-DCs) was lower than that with albumin-treated DCs (Alb-DCs). Direct addition of AFP to NK cells did not alter the cytolytic activity of NK cells. Adding AFP inhibited the interleukin (IL)-12 production of DCs after stimulation with lipopolysaccharide (LPS) [Toll-like receptor (TLR)-4 ligand], or Poly(I:C) (TLR-3 ligand), but not IL-18 production. The mRNAs of IL-12p35 and IL-12p40 were significantly inhibited in AFP-DCs compared with Alb-DCs, but those of TLR-4 or TLR-3 were not. Transwell experiments revealed that soluble factors derived from DCs played roles in inhibition of the ability of activating NK cells by AFP-DCs. Adding the neutralizing antibody of IL-12 to NK cells co-cultured with Alb-DCs resulted in a decrease of cytolytic activity to the levels of NK cells co-cultured with AFP-DCs. Adding IL-12 to NK cells co-cultured with AFP-DCs resulted in an increase of cytolytic activity to the levels of NK cells co-cultured with Alb-DCs. These demonstrated that the impairment of IL-12 production from AFP-DCs resulted in inhibition of the ability of the activation of NK cells by DCs, and thus suggests a role of AFP in HCC development.

Splenectomy and antiviral treatment for thrombocytopenic patients with chronic hepatitis C virus infection.

Thrombocytopenic patients with chronic hepatitis C virus (HCV) infection are poor candidates for antiviral treatment with interferon (IFN), but no standard treatment for thrombocytopenia has yet been established. We evaluated the safety of splenectomy and its efficacy for the initiation and continuation of antiviral therapy. From March 2003 to April 2006, 10 patients (mean age 62.5 years) with HCV-related cirrhosis, low platelet count (<==106 000/mm(3)) and splenomegaly (spleen size >==10 cm) underwent splenectomy. Platelet counts significantly increased at 4-8 weeks after splenectomy [pre: 64 200 +/- 6900/mm(3)vs post 209 000 +/- 40 600/mm(3) (P = 0.004)]. No severe operative complications were observed. All patients subsequently received antiviral therapy. Of the eight patients who were infected with HCV genotype 1 and had a high viral load (>==100 KIU/mL), four received combination therapy with pegylated IFNalpha-2b plus ribavirin, and the other four received standard IFNalpha-2b plus ribavirin. One patient infected with HCV genotype 2 and another with HCV genotype 1 and a low viral load (<100 KIU/mL) were treated with pegylated IFNalpha-2a. Six patients achieved sustained virologic response (SVR). Among four patients who failed to achieve SVR, one was given retreatment with pegylated IFN plus ribavirin, and the other three received low-dose long-term IFN therapy. Although this study was small, the treatment results were similar to those for patients without thrombocytopenia and suggested that splenectomy would not reduce the antiviral efficacy of IFNalpha-based treatment.