抄録
The immune function in cancer patients is suppressed, however, the factors that promote this suppression are still obscured. We hypothesized that polyamine is one of the causative factors of the immune suppression, as polyamine levels in blood and tissues are increased in cancer patients. In this study, the effects of increased polyamine concentration on cellular immunity were investigated. For this, human peripheral blood mononuclear cells (PBMCs) from volunteers were cultured in RPMI-1640 medium supplemented with 10% human serum. Freshly prepared polyamine was added to cultured PBMCs at various concentrations, and their effects on the production of tumor necrosis factor (TNF), adhesion capacities, and cytotoxic activities upon stimulation with interleukin-2 were examined. Spermine and spermidine, but not putrescine, immediately suppressed lipopolysaccharide-stimulated TNF production in a dose-dependent manner. PBMCs cultured either with spermine or spermidine decreased their ability to adhere to plastic. The decreases in adhesion capacity were observed in a dose-dependent manner, but were not observed in PBMCs cultured for 24 hours with spermine and spermidine. PBMCs cultured overnight with spermine and spermidine decreased their cytotoxic activities. Spermine and spermidine did not affect the cell viability. These suggest that the increased polyamine levels in cancer tissues and in blood may be one of the factors that hinder the immune function of cancer patients.
