To explore the frequencies of peripheral blood CD4(+);CD25(high);Treg and CD4(+);CD25(low);T cells and the expression of the co-stimulatory molecule PD-1 on these two group cells surface in SLE and RA patients, and to explore their roles in cell immunity disorder of SLE and RA.
Flow cytometry (FCM) was used to determine the frequencies of peripheral blood CD4(+);CD25(high);Treg and CD4(+);CD25(low);T cells, and the expression percentage of PD-1.
Compared with healthy control, the frequencies of peripheral blood CD4(+);CD25(high);Treg from both SLE and RA patients groups decreased significantly(P<0.05). Compared between two disease groups, the frequency of peripheral blood CD4(+);CD25(high);Treg in SLE patients was significantly lower(P<0.05). The expression percentage of PD-1 on CD4(+);CD25(high);Treg surface in RA group was obviously lower than that in both healthy control and SLE patients groups(P<0.05), while the percentage had no significant difference between SLE patients and healthy control(P>0.05). There was no significant difference in both the frequency of CD4(+);CD25(low);T cells and the expression percentage of PD-1 on this subset cells among three groups.
The weakened ability of peripheral blood CD4(+);CD25(high);Treg to suppress effector T cells resulted from their production deficiency is the common characteristic of SLE and RA patients. Decreased expression of PD-1 is the primary cause leading to the suppressive function of peripheral blood CD4(+);CD25(high);Treg weakened in RA patients. However, PD-1 does not play major role in weakening the suppression activity of CD4(+);CD25(high);Treg from SLE patients.