Lymph invasion route of bacteria and endotoxin and CD4+/CD8+ T cells ratio changes of draining lymph node of burn infection wound

The aim of this study was to determine the lymphatic invasion route of bacteria and endotoxin of burn wounds infected by Pseudomonas aeruginosa and moreover, the effect of P. aeruginosa infection of the burn wound on the draining lymph node and lymph fluid. Male Wistar rats were subjected to unilateral hind limb burn + wound infected by P. aeruginosa (infection limbs group) and contralateral hind limb burn alone (burn limbs group). On hours 6, 24 and 72 after infection, rats were killed, the common iliac lymph nodes (CILN) was collected for the culture of P. aeruginosa. Lymph fluid in the efferent lymph trunk of CILN was collected for the measurement of endotoxin by the Limulus Amebocyte Lysate test. Lymph fluid tumor necrosis factor-alpha (TNF-α) concentration was measured by enzyme-linked immunosorbent assay (ELISA). The CD4+/CD8+ T cells ratio of CILN was subjected to flow cytometry analysis. The results showed bacteria invasion incidence, endotoxin and TNF-α concentrations were significantly higher in the infection limb group when compared to the burn limb group (P < 0.01). The CD4+/CD8+ T cell ratio was significantly lower on post-burn wound infection hours 72 (P < 0.05). This study provides evidence that bacteria and endotoxin of burn wound infected by P. aeruginosa invade draining lymph node and lymph fluid. P. aeruginosa infection of the burn wound can increase TNF-α level of the draining lymph fluid and decrease CD4+/CD8+ T cells ratio of the draining lymph node.