AIM: To evaluate the immunohistochemical localization of interleukin-6 (IL-6) and IL-6 receptor (IL-6R) on tumor tissue specimens from patients with hepatocellular carcinoma (HCC) and the serum levels of IL-6 and sIL-6R in a group of patients with HCC as well as liver cirrhosis (LC) in a group of patients with LC alone and in a control group. METHODS: Three groups of subjects were studied: groupⅠ(n=83) suffering from HCC and LC, groupⅡ(n=72) suffering from LC alone and groupⅢ(n=42) as healthy controls. All patients had hepatitis C virus infection. Serum IL-6 and IL-6R levels were determined using a commercially available ELISA kit. Immunohistochemistry was performed using the streptavidin-biotin complex and rabbit polyclonal antibodies against IL-6 and IL-6R. RESULTS: Immunohistochemistry analysis showed a medium to strong cytoplasmic and membrane reactivity for IL-6 and IL-6R respectively, in at least 40% of cases of HCC, whereas liver cirrhosis patients and controls were negative for IL-6 or showed a very mild and focal dot-like cytoplasmic reaction for IL-6R. Serum IL-6 levels in HCC group were significantly higher than those in LC and control groups (P<0.0001). There was no significant difference in sIL-6R concentrations among 3 groups. When the patients with HCC were divided into groups according to Okuda’s classification, a significant serum increase of IL-6 and sIL-6R level was observed from stageⅠto stageⅢ(P<0.02,P<0.0005). When HCC and LC patients were divided into 3 classes of cirrhosis severity according to Child-Pugh, values in HCC patients were significantly higher than those in LC patients for each corresponding class (P<0.01). CONCLUSION: IL-6 serum levels in HCC patients are higher than those in LC patients and controls, suggesting an increased production of this cytokine by neoplastic cells. sIL-6R values are similar in all groups, increasing only in stageⅢHCC patients. These data suggest that they have a closer relationship with the neoplastic mass rather than with the residual functioning hepatic mass. AIM: To evaluate the immunohistochemical localization of interleukin-6 (IL-6) and IL-6 receptor (IL-6R) on tumor tissue specimens from patients with hepatocellular carcinoma (HCC) and the serum levels of IL- 6 and sIL-6R in a group of patients with HCC as well as liver cirrhosis (LC) in a group of patients with LC alone and in a control group. METHODS: Three groups of subjects were studied: group I (n = 83) suffering from HCC and LC, All patients who had hepatitis C virus infection. Serum IL-6 and IL-6R levels were determined using a commercially available ELISA kit. Immunohistochemistry was performed using the streptavidin-biotin complex and rabbit polyclonal antibodies against IL-6 and IL-6R. RESULTS: Immunohistochemistry analysis showed a medium to strong cytoplasmic and membrane reactivity for IL-6 and IL-6R respectively, at least 40% of cases of HCC, and liver cirrhosis patients and controls were negati ve for IL-6 or showed a very mild and focal dot-like cytoplasmic reaction for IL-6R. Serum IL-6 levels in HCC group were significantly higher than those in LC and control groups (P <0.0001). difference in sIL-6R concentrations among 3 groups. When the patients with HCC were divided into groups according to Okuda’s classification, a significant serum increase of IL-6 and sIL-6R level was observed from stageⅠto stage Ⅲ (P <0.02, P <0.0005 When HCC and LC patients were divided into 3 classes of cirrhosis severity according to Child-Pugh, values ​​in HCC patients were significantly higher than those in LC patients for each corresponding class (P <0.01). CONCLUSION: IL-6 serum levels in HCC patients are higher than those in LC patients and controls, suggesting an increased production of this cytokine by neoplastic cells. sIL-6R values ​​are similar in all groups, increasing only in stage IIIHCC patients. These data suggest that they have a closer relationship with the neo plastic massrather than with the residual functioning hepatic mass.