CD4 and in situ carcinoma: Moreover, the changes in 5-HT and its metabolite, 5-HIAA, within the hippocampus in response to the repeated stress treatment differed as a function of the significant interaction between the CD4+CD25+ Treg cell depletion and the CIS among the control group and anti-CD25 Ab-treated group (F1, 21 = 5.02, p = 0.0359 and F1, 21 = 4.472, p = 0.0466), but no significant effect of the CD4+CD25+ Treg cell depletion or CIS on the 5-HT (F1, 21 = 0.67, p = 0.4236 and F1, 21 = 0.003, p = 0.9523) and 5-HIAA levels (F1, 21 = 0.06, p = 0.8040 and F1, 21 = 1.72, p = 0.2043) were observed.