OBJECTIVETo observe the effect of burn on cytokines in lymph and T lymphocyte subsets in lymph node of rats.

METHODSEighteen Wistar rats were used in the experiment. One of the hind limbs of each rat was immersed in 70 °C hot water for 30 s to reproduce 4%TBSA deep partial-thickness scald model (burn group), while the other hind limb was immersed in 22 °C warm water for 30 s to simulate scald (sham injury group). On post injury hour (PIH) 6, 24, and 72, 6 rats were chosen according to the random number table. Lymph fluid in the lymph vessel of each animal (two groups) was obtained for determination of levels of tumor necrosis factor α (TNF-α), interferon-γ (IFN-γ) and interleukin-4 (IL-4) by ELISA, and IFN-γ/IL-4 ratio was calculated. Common iliac lymph node of each animal (two groups) was obtained for determination of ratios of CD4(+), CD8(+)T lymphocytes with flow cytometry, and CD4(+)/CD8(+) ratio was calculated. Data were processed with t test.

RESULTS(1) On PIH 6, 24, and 72, TNF-α level in burn group was respectively (51.6 ± 5.4), (27.4 ± 2.6), (23.0 ± 2.7) pg/mL, which were significantly higher than those in sham injury group [(17.8 ± 1.6), (16.4 ± 1.2), (17.2 ± 2.0) pg/mL, with t value respectively 15.346, 11.854, 4.189, P values all below 0.01]. (2) On PIH 6, 24, and 72, there was no significant statistical difference between burn group and sham injury group in IFN-γ level (with t value respectively 2.059, -0.805, -0.415, P values all above 0.05); IL-4 level in burn group was respectively higher than that in sham injury group (with t value respectively 9.141, 11.669, 6.940, P values all below 0.01); IFN-γ/IL-4 ratio in burn group (2.27 ± 0.34, 1.54 ± 0.19, 1.60 ± 0.16) was respectively lower than that in sham injury group (3.33 ± 0.25, 3.34 ± 0.22, 2.52 ± 0.24, with t value respectively -6.298, -11.313, -8.893, P values all below 0.01). (3) On PIH 6 and 24, there was no significant statistical difference between burn group and sham injury group in ratios of CD4(+) and CD8(+)T lymphocytes and also CD4(+)/CD8(+) ratio (with t values from -2.486 to -0.215, P values all above 0.05). On PIH 72, ratio of CD4(+)T lymphocytes and CD4(+)/CD8(+) ratio in burn group was respectively (38.6 ± 2.3)% and 2.13 ± 0.16, which were significantly lower than those in sham injury group [(48.9 ± 2.9)% and 2.68 ± 0.12, with t value respectively -7.551, -5.068, P values below 0.01]; there was no significant statistical difference between burn group and sham injury group in ratio of CD8(+)T lymphocytes (t = 0.845, P > 0.05).

CONCLUSIONSBurn may decrease IFN-γ/IL-4 ratio in locally drained lymph and CD4(+)/CD8(+) ratio in locally drained lymph node of rat, which may indicate lowering of local immune function.