Serum Immunosuppressive Acidic Protein as an Interleukin-6 Related Index of Deteriorating Condition in Gastric Cancer Patients

Abstract

Background/Aims: Immunosuppressive acidic protein (IAP) is an acute-phase reactant which has a close correlation with the impairment of the host’s immunity. The present study aims to investigate the significance of serum IAP as an index of cytokine-related disease status in gastric cancer patients. Methods: Serum IAP levels were determined in 76 gastric cancer patients and 20 healthy subjects. In a subgroup of 39 patients, tissue interleukin-6 (IL-6) concentrations and expression of IL-6 protein in tumor tissues were also examined. Results: The mean serum IAP level in the patients was significantly higher than that in the normal controls. The serum IAP level in the patients was associated with clinicopathological features, such as tumor size and serosal invasion. The prognosis of patients with high IAP levels was significantly worse than that of those with low IAP levels. Moreover, the serum IAP level was closely correlated with various parameters reflecting the host’s nutritional and immunological conditions. Immunohistochemically, IL-6 was overexpressed in the cytoplasm of tumor cells. The IL-6 concentration and immunoreactivity of IL-6 protein in tumor tissue was significantly correlated with the serum IAP level. Conclusions: Elevated serum IAP, which may be upregulated by an activated IL-6 network in tumor tissue, may reflect not only tumor progression, but also a deteriorated condition that is associated with malnutrition and immunosuppression in gastric cancer patients.