HBO2 induced changes in CD4+ and CD8+ T cell frequencies in the colon of BALB/c mice with DSS induced colitis. BALB/c mice at the age of 10–12 weeks were randomly assigned into 4 groups (n = min. 4 mice/group/experiment): CTRL: control mice, CTRL + HBO2: control mice undergoing HBO2 (60 min/2.4 ATM, 2x/day, days 1–8), DSS: mice receiving dextran sodium sulphate (DSS, 5% w/v, days 1–7), and DSS + HBO2: DSS treated mice undergoing HBO2. (a) Representative dot plots of colon lamina propria lymphocyte obtained by flow cytometry, illustrating the gating strategy for CD4+ and CD8+ lymphocytes, and (b) measured frequencies of colon CD4+ and CD8+ lymphocytes. Doublets were excluded by forward scatter area (FSC-A) versus forward scatter height (FSC-H) and the dead cells using 7-AAD. Data are presented as mean ± s.e.m.% of single, live lymphocytes. ∗Statistically different from CTRL, P < 0.05; †statistically different from CTRL + HBO2.