Objective To Analyze the immunity to secondary infection in the elderly with severe acute pancreatitis.Methods Totally 105 old patients were included in the present study.The ratio of CD4+ to CD8+,and serum levels of tumor necrosis factor-α (TNF-α),interleukin-6 (IL-6),interleukin-10 (IL-10),and interleukin-4 (IL-4) were determined by flow cytometer analysis or ELISA within 3 days after diagnosis of secondary infection.Results Among 105 old patients,58 cases experienced secondary infection.At 3th day after severe acute pancreatitis,the levels of TNF-α,IL-6,IL-4,IL-10,CD4+,CD8+ and CD4+/ CD8+ were (81.3±5.5)ng/L,(141.2±13.7)ng/L,(61.1±7.4) ng/L,(153.8 ±15.2) ng/L,(43.5±5.5)％,(20.7±2.9)％ and (2.4±0.3) in infection group,as compared with those of (50.8±4.7)ng/1,(81.4±11.7)ng/L,(30.8±7.8)ng/L,(100.3± 13.8)ng/L,(31.6±4.6)ng/L,(29.7±3.5)and (1.1±0.4)in control group,respectively,with statistically significant differences betwveen the two groups (t=7.30,6.51,4.87,4.52,2.88,3.41,4.26,all P＜0.05).At 28th day after SAP,the levels of TNF-α,IL-6,IL-4,IL-10,CD4+,CD8 ± and CD4+ /CD8+ were (29.3±5.8)ng/L,(51.7±7.9)ng/L,(33.8±5.1)ng/L,(82.6±9.5)ng/L,(22.1±3.3)％,(47.1±4.3)％ and (0.6±0.3) in infection group,as compared with those of (44.4±5.5)ng/L,(82.2±7.1)ng/L,(65.3±5.5)ng/L,(109.1±9.5)ng/L,(40.5±2.7)ng/L,(33.4±4.5)ng/L and (1.8±0.4) in control group,respectively,showing statistically significant differences between the two groups(t=3.26,4.93,7.32,3.43,7.41,3.81,4.33,all P＜0.05).Conclusions An early excessive immune response and subsequent immune injury is closely related to secondary severe acute pancreatitis.

Objective To investigate changes and the significance of Th17/Treg immune imbalance in secondary systemic infection in patients with severeacute pancreatitis.Methods We selected 21 patients with severe acute pancreatitis and secondary systemic infection (infection group),25 patients with severe alone (non-infection group),20 healthy cases undergoing annual health checkup (control group) in this study.The expression levels of Th17/Treg cells and related cytokines were compared between groups.Results There were significant differences in mortality rate and duration of ICU stay between infection group and non-infection group [23.8％ vs.4.0％,(11.3±3.4) d vs.(7.5±2.8) d,x2=3.949,t=2.890,P=0.047 and0.045].The percentages of Th17 cell andTreg cell,Th17/Treg ratio,mRNA expressions of IL-6,IL-17,IL-23,TGF-β and orphan receptor γt were higher in infection and non infection groups than in control group [(26.4 ± 1.2) ％,(12.8 ± 0.9)％ vs.(3.1±0.8) ％;(6.7±1.6)％,(4.2±1.3)％ vs.(1.3±0.4)％;(4.3±1.0)％,(3.2±1.1)％ vs.(2.4±0.9)％;(7.1±0.8)ng/L,(5.3±0.7)ng/L vs.(0.2±0.1)ng/L;(22.9±2.4)ng/L,(15.6±2.8)ng/L vs.(10.3± 1.5)ng/L;(15.7±2.1)ng/L,(10.2± 1.5)ng/L vs.(8.3± 1.4)ng/L;(23.6±2.2)ng/L,(16.3±1.7)ng/L vs.(11.6±1.1)ng/L;(0.052±0.014),(0.035± 0.010) vs.(0.004±0.001);F=15.761,55.745,9.437,102.788,21.038,16.239,36.957,23.924,respectively,P=0.555,0.000,0.014,0.000,0.002,0.004,0.000,0.000].The mRNA expressions of IL-10 and Foxp3-T were lower in infection and non-infection groups than in control group [(6.4±1.1)ng/L,(10.5 ± 2.1) ng/L vs.(15.4±2.0)ng/L;(0.005±0.001),(0.020±0.007) vs.(0.032±0.009),F=18.995 and 20.608,P=0.003 and 0.002].Conclusions The secondary infection can aggravate the Th17 / Treg immune imbalance in patients with severe acute pancreatitis,and extend the ICU hospitalization days.