Abstract: Abstract：Objective To study the effect of laparoscopic neoplasty and changes of procalcitonin (PCT) and cellmediated immunity in elderly patients with duodenal ulcer perforation. Methods Forty-four elderly patients with duodenal ulcer perforation were divided into laparoscopic neoplasty group (n=20) and open neoplasty group (n=24)．The level of PCT was assayed by colloid immunization. Blood levels of CD3+, CD4+, CD8+ and natural killer (NK) cells were detected by flow cytometry before operation and at 0.5 h, 24 h, 48 h and the 7th day after operation．Surgical complications and postoperative hospital stay were observed in two groups. Results There was no significant difference in the activity of PCT before operation between two groups. There were no significant differences in CD3 + , CD4 + , CD8 + and NK cells 0.5 h before operation between two groups. The level of PCT was significantly lower at 24 h and 48 h after operation in laparoscopic group than that in open operation group (P< 0.05). There were significant differences in the serum levels of CD3+, CD4+, CD8+ and NK cells with time changes in two groups (P＜0.05). There were significant decreases in CD3+, CD4+ and CD8+ at 24 h after operation than those before operation in two groups, which were significantly lower in open operation group than those of laparoscopic group except for CD8+. The levels of CD3+, CD4 + and CD8+ recovered to the levels before operation at 48 h after operation in laparoscopic group. In open operation group CD3+ did not return to the level before operation at 7 d after operation. The levels of NK cells were decreased at 24 h after operation in two groups, but there was no significant difference in the level of NK cells between two groups. The level of NK cells returned to preoperative levels at 48 h after operation inlaparoscopic group, while there was no significant difference in the level of NK cells before and after operation in open neoplasty group. Compared with the open neoplasty group, there were fewer complications and shorter hospital stay in laparoscopic group. Conclusion The laparoscopic repair operation for gastric and duodenal ulcer perforation has a fewer effects on the stress response and immune function in elderly patients, and has the advantages in the protection of immune function.

Key words: peptic ulcer perforation, laparoscopy, immunity, cellular, T- lymphocyte subsets, killer cells, natural, procalcitonin