Abstract: Objective To investigate the changes of interleukin-8(IL-8), tumor necrosis factor-α(TNF-α), matrix metalloproteinase-9(MMP-9) and T-lymphocyte subsets in plasma of patients with paraquat poisoning and the effect of ulinastatin on the above indicators, in order to study the curative effect of ulinastatin on paraquat poisoning and provide a new method for the treatment of paraquat. 
Methods A total of 80 patients meeting the criteria of acute paraquat poisoning were selected and divided into two groups: poisoning group(n=40) and treatment group(n=40). The patients in the poisoning group received conventional treatment, while the other group received ulinastatin in addition to the basic treatment. The clinical indicators of the two groups were observed at 14 d after treatment, and the blood samples were collected at 7 d and 14 d after treatment. The levels of IL-8, TNF-α and MMP-9 in plasma were detected. The levels of CD3+, CD4+, CD8+ and the ratio of CD4+/CD8+ in peripheral blood were detected by SAP enzyme labeling method. 
Results The incidence of acute respiratory distress syndrome(ARDS), survival rate, duration of ICU stay and survival time of dead patients in the treatment group were better than those in the poisoning group(P＜0.05). Compared with the poisoning group, the levels of IL-8, TNF-α, MMP-9 and CD8+ in the treatment group were significantly decreased(P＜0.05), while CD3+, CD4+, and CD4+/CD8+ were significantly increased, suggesting significant difference(P＜0.05). 
Conclusion Ulinastatin can improve the clinical efficacy of patients wiht paraquat poisoning, and its underlying mechanism may be related to its inhibition of the release of inflammatory factors and regulation of immune function of T-lymphocyte subsets, with obvious effect. Therefore, it is worthy of clinical promotion.

Key words: paraquat, ulinastatin, T-lymphocyte subsets