| Objective: A 30% TBSA , full-thickness scald model of rats was employed to determine the type-l/type-2 cytokines response of helper T lymphocytes after thermal inhury and to investigate the effects of escharectomy during burn shock stage on the polarization of Th cells and host immune function. The mRNA and protein levels of interleukin(IL)-2, IL-4, IL-10 and interferon-gamma ( IFN-y ) and the proliferative response of T lymphocytes was also measured. In addition, in vito study was performed to observe the potential effect of serum from scalded animals and eschar extracts on Thl/Th2 cytokine response as well as T lymphocyte proliferation. The main objective of the present study was to demonstrate the endanger effect of long-term existent of eschar and the necessary of escharectomy during burn shock stage. Material and Method: In the experiment 1, 160 male Wistar rats, weighing 180 to 220g, were acclimatized for a period of one week and randomized into four groups. In group A, animals weren't subjected to escharectomy. In groups B, C and D , escharectomy and skin allograft was done at 8, 24, 96 hours postburn(PB) respectively. At 4, 12, 24, 48, 96, 120 and 168h PB.animals were killed and bloods samples,spleens as well as mesenteric lymph nodes (MLN) were harvested. Splenocytes were isolated from spleen aseptically. In the experiment 2, splenocytes of healthy rats were stimulated with serum from burned/healthy rats and extracts isolated from eschar/normal skin with the method described by Schoenenberger. Tcells and supernatants were harvested respectively. For all samples of both experiment, ELISA was applied to determine levels of IFN-γ and IL-10 in blood, spleen and MLN and IL-2 and IL-10 levels in the same samples were examined by radio immunoassay. IFN-γ, IL-4 mRNA and protein expression were respectivelydetermined by RT-PCR and immunohistochemistry staining in spleen, MLN as well as T lymphocytes. T lymphocytes proliferative response was assayed by H-TdR incorparation .Results: 1. In all groups, the levels of IFN-γ, IL-2, L-4 and IL-10 rapidly and significantly increased after scald injury. IFN-γ and IL-2 levels began to rise within 4h postburn, peaking at 24h postburn. IL-4 and IL-10 showed a prolonged (from 12h PB) while persistant elevation.. In group A all above parameters revealed most obvious changes compared with controls, then ranked in group D,B and C. 2. The mRNA expression of these cytokines were all markedly higher, corresponding to the change in lymphokines protein levels. 3.T lymphocyte proliferative response was significantly suppressed after burns .but whicn in group B was markedly impeoved than those in the other groups. 4. In supernatants of T lymphocytes stimulated in vitro by serum from burned animal ,there was a significant increase in IFN-γ, IL-2, IL-4 and IL-10 levels, so was the mRNA expression. Proliferation of the stimulated T cells was inhibited at the same time. Serum from healthy rats had no marked influence on T lymphocyte response. 5. Reactions of T cells stimulated in vitro by eschar extracts were similar to that stimulated by serum from burned animals, in contrast, normal skin extractis didn't show any effect. Conclusion:1.Thermal injury per se could result in a rapidly increase of Th1/Th2 lymphokines together with up-regulation of cytokine mRNA expression.2. Th1 cytokines decreased on postbum day 1, whereas Th2 cytokines kept time-dependently elevation, thereby leading to a dominant tendency of Th2 cytokine response.3. Proliferation of T lymphocytes was severely depressed following major burns.4. Escharectomy could obviously modulate the marked change of Thl/Th2 cytokines, especially reduce the risk of imbalance between Th1 and Th2 lymphokines. It was demonstrated that the earlier escharectomy was undergone, the better effect was achieved.5. Serum from burned rats could promote the capacity of T lymphocyte to produce Thl and Th2 cytokines, but such effect would be reduced if the serum was obtained from animals underwent escharectomy dur...
|
PDF Full Text Request