[Dynamic changes in cytokines in wound exudates from superficial II degree burns in rats]

We take rats as models to study the dynamic changes in cytokines in wound exudate at different time phases post-burn. 120 SD rats were divided into two groups: group 1 with subcutanous implantation of sponges only (S), and group 2 rats were inflicted 10% superficial II degrees burns of their total body surface immediatly after the implantation (Sb). The activities of IL-1, IL-6 and TNF alpha in wound exudates within sponges were measured at 6 h, 1 d, 3 d, 7 d, 10 d and 14 d after the injuries. The changes in activity of these cytokines in both groups showed somewhat the same type of fluctuations, i.e., temporarly ebb and flow in the early phases, and 72 hs later showing a steady increase. The activity of IL-6 reached the peak level in 6 hs while IL-1 and TNF alpha in 24 hs. Probably the early peak levels were produced by local cells responding to the injuries. At each peak level, there was an apparent difference between group S and group Sb (p < 0.01). In the early phases, the levels were S > Sb, and later, the reverse. In group S there was a positive correlation between IL-1 and IL-6, whereas in Sb only 6 h's exudate showed a weak positive correlation. We think the cause of the early differences was: 1. less number of cytokine secreting cells in Sb due to severer injury to local tissues, and 2. increased capillary permeability releasing cytokines from local tissues to the surroundings. The late differences suggest that repair was more complicated and time-consuming in Sb.