[Effects of hyperbaric oxygen on T lymphocyte subpopulation and its electron microscopic changes in rats with acute...

To investigate the effect of hyperbaric oxygen (HBO) therapy on T lymphocyte subpopulations in rats with acute pancreatitis (AP).

According to random number table, 56 Sprague Dawley (SD) rats were divided into three groups: the sham group, model group, and HBO therapy group. The rats of model and HBO groups underwent pancreatic duct ligation to induce pancreatitis, then they were divided into three subgroups of 8 rats each. The HBO group was treated with a daily exposure to HBO [2.5 atm (1 atm=101.325 kPa)]. The rats in each subgroup were euthanased on days 1, 3, 7, and the subpopulations of T lymphocytes in peripheral blood were detected respectively using flow cytometry. The nuclei, mitochondrion, rough and smooth endoplasmic reticulum of the pancreatic cells were examined using electron microscopy.

The serum level of amylase on day 1 in model and HBO groups was significantly lower than that in sham group. In the model group the CD4(+)CD8(+) cells and the CD4(+)/CD8(+) ratio in AP rats was significantly decreased, indicating the presence of immune suppression. After 7 days of HBO therapy, compared with the model group, the CD4(+) lymphocytes in the HBO group were markedly increased on day 3 and day 7 [(27.92±2.10)% vs. (20.79±2.80)%, (26.58±4.50)% vs. (17.76±4.40)%]. The number of CD8(+) lymphocytes were also increased to a certain extent on day 7 [(25.32±3.70)% vs. (22.46±3.10)%]. The CD4(+)/CD8(+) ratio was obviously increased on day 3 and day 7 (1.07±0.14 vs. 0.86±0.15, 1.04±0.11 vs. 0.79±0.12, P<0.05 or P <0.01). Also beneficial effects as evaluated on the nuclei, mitochondrion, rough and smooth endoplasmic reticulum were found in the HBO group (10.8±1.6 vs. 17.9±1.7, 22.1±1.6 vs. 27.5±1.3, 16.8±1.0 vs. 29.3±0.8, 21.2±1.4 vs. 28.7±1.2, all P <0.01).

This study shows that 7-day HBO therapy can promote a more balanced profile of T lymphocyte subpopulations, resulting in improvement of cellular immune function, and it can ameliorate pathological changes as shown by electron microscopic examination.