Frequencies of CD4+ T Regulatory Cells and their CD25(high) and FoxP3(high) Subsets Augment in Peripheral Blood of Patients with Acute and Chronic Brucellosis

Brucellosis remains one of the most common zoonotic diseases worldwide. In humans, brucellosis can be a serious, debilitating, and sometimes chronic disease. Different mechanisms can be postulated as to the basis for the induction of the chronic status of infectious diseases that T regulatory cells are one of the most important related mechanisms. The current study was designed to determine whether percentage of CD4+Treg cells and their CD25(high) and FoxP3(high) subpopulations in peripheral blood are changed in human brucellosis samples in comparison to a control group. In total, 68 brucellosis patients (acute form: n = 43, chronic form: n = 25) and 36 healthy volunteers entered our study. After isolating of peripheral blood mononuclear cells, heparinized venous blood samples were obtained from both patients and healthy donors, CD4, CD25, and FoxP3 molecules were evaluated by two- and three-color flow cytometric methods. The results revealed a new finding in relation to Treg cells and human brucellosis. The numbers of CD4(+)Treg cells and their CD25(high) and FoxP3(high) subsets increase significantly in the peripheral blood of acute and chronic forms of brucellosis samples compared with healthy groups, with this increase being greater in the chronic group. There seems to be a correlation between increase of CD4+Treg cells and their subsets and the disease progress from healthy state to acute and chronic brucellosis.