Measurement of interleukin-6, interleukin-10, and tumor necrosis factor-alpha levels in tissues and plasma after thermal injury in mice☆

Abstract Background . Cytokines are important modulators of physiologic alterations after thermal injury. Indeed, an increase in the level of circulating cytokines has been documented after thermal injury. However, the mechanism of the increase has not been clarified. We determined cytokine levels in local tissue after thermal injury to identify the tissues responsible for the increase. Methods . Female C57BL/6 mice each received a 20% full-thickness burn injury. Blood, burned skin, unburned skin, muscle underlying the burn, and muscle of the thigh, liver, spleen, and mesenteric lymph node were sampled at 1, 2, 4, 8, and 24 hours after injury. Uninjured control mice were treated similarly. The samples were cultured, and concentrations of tumor necrosis factor-α, interleukin-6 (IL-6), and IL-10 in the culture media were measured by using an enzyme-linked immunosorbent assay. Results . IL-6 levels in unburned skin were significantly increased at 1 hour and decreased at 24 hours, compared with the control. IL-6 levels in muscle underlying the burn were significantly decreased at 8 hours. No elevation of plasma IL-6 levels was observed after injury. Neither tumor necrosis factor-α nor IL-10 was detected in any tissue. Conclusions . Results indicate that unburned skin may be a major source of IL-6 production after thermal injury and may contribute to the physiologic alterations occurring after such injury.