Circulating level of regulatory T cells in rheumatic heart disease: An observational study.

BACKGROUND: The regulatory T cell (Treg) is essential for prevention of autoimmunity. In a preliminary study, we showed significant deficiency of Tregs (CD4CD25 T cells) in rheumatic heart disease (RHD) patients (an autoimmune disease), but the markers used could not reliably differentiate Treg from nonregulatory conventional T cells (Tcon). The study aim was to reassess the level of circulatory Tregs by using more specific markers.

METHODS: 70 adults of RHD and 35 controls were studied. Patients were subdivided according to the extent of left-sided valvular involvement. 35 patients with significant mitral-valve disease only were enrolled in the univalvular group while 35 patents with significant involvement of both mitral and aortic-valves in the multivalvular group. Circulating Treg cell level was determined by flow-cytometry.

RESULTS: Level of Tregs (CD4+CD25(med-high)CD127(low) Foxp3(high)) in CD4+ T lymphocyte was significantly lower in RHD patients compared to controls (median 0.6% versus 3.2%; p=0.001) with no significant difference in Tcon cells (p=0.94). Within the study group Treg count was significantly lower in patients with multivalvular-disease only (median 0.1% versus 3.2%; p=0.001) with no significant difference in Treg cell count between the univalvular group and control (median 1.9% versus 3.2%, p=0.10).

CONCLUSION: There is significant deficiency of circulating Tregs in patients of chronic RHD and the deficiency is greater in patients with multivalvular than univalvular involvement.