Dynamic changes of interleukin-1, interleukin-6 and tumor necrosis factor in intermingled skin graft in burned rats

To compare the dynamic changes of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF) in intermingled skin graft with those in other types of skin grafts in rats.

A 10%-15% third-degree burn was created in 180 Sprague-Dawley (SD) rats. After removing the scar, skin grafts were performed on the open wounds immediately with autoskin (aus, n=54), alloskin (als, n=54) and intermingled skin (n=36). That is to say, in the intermingled skin graft, a big piece of alloskin (mals) was grafted first, and 3 days later, small pieces of autoskin (maus) wer e embedded in the alloskin. The rest 36 rats were taken as the controls. And the biological activities of IL-1, IL-6 and TNF in graft sheets in each group were detected after skin graft.

The levels of IL-1, IL-6 and TNF in the aus group decreased steadily after their initial elevations, whereas in the als group they increased significantly and kept on the peak level in the later phases. In the in termingled group, there appeared a lowest IL-1 level in the mals and a highest one in the maus simultaneously at 7 (4) days (The number out of parenthesis is t he days after transplanting with alloskin sheets, and the number in parenthesis is the days after embedding autoskin sheets in the intermingled skin graft. Similarly hereinafter.) after skin graft (P<0.01), and the high level in the maus abruptly decreased at 14 (11) days after skin graft. At exactly the same phase on day 7 (4), a prominent peaked IL-6 in the mals occurred. In the later phases, the levels of TNF remained relatively low both in the m als and in the maus. From day 7 (4) on, each cytokine fluctuation in the mals synchronized with that in the maus. The longer the post transplantation period lasted, the more the positive cytokine correlated between the mals and the maus.

The low levels of IL-1 and TNF may be important f actors to lighten the intensity of local rejection in the intermingled skin graft. The temporarily peaked IL-6 is both an inducer which induces the production of local IL-1 receptor antagonists and soluble TNF receptors and a signal which indicates a local enhancement of Th(2) cells. The mild rejection process and th e synchronized cytokine level during the later phases suggest a possible chimerism between the mals and the maus.