Expression and clinical significance of PD-1 on CD4+CD25high Tr and CD4+ CD25low T cells in the peripheral blood of patients with systemic lupus erythematosus
Objective To detect the frequency of peripheral blood CD4+ CD25high Tr and CD4+CD25lowT cells and expression of programmed death-1 ( PD-1 ) on their surface in the patients with systemic lupus erythematosus(SLE) and their clinical signifcance is analyzed.Methods The expression of PD-1 on the CD4+ CD25highTr and CD4+CD25lowT cells was examined in patients with 33 active SLE,18 inactive SLE and 38 healthy controls(HC) by flow cytometry.Clinical manifestations and laboratory findings of SLE were collected.Patients were divided into two groups according to their disease activity.SLE disease activity index(SLEDAI) score≥10 was defined as high disease activity and ＜10 as inactivity.The percentage of CD4+ CD25highTr and CD4+CD25lowT cells and proportions of expression of PD-1 on their surface were compared between not only inactive or active SLE patients and healthy controls (HC),but also between patients with lupus nephritis and without lupus nephritis.Correlation with clincal manifestations and laboratory findings was analyzed.Results (1)The proportions of CD4+CD25highTr and CD4+CD25low T cells were significantly decreased in active and inactive SLE patients as compared with HC.(2)The percentage of CD4+ CD25lowPD-1 +Tr and in active and inactive SLE patients were higher than HC.The proportions of CD4+CD25lowPD-1+ T cells were significantly increased in HC and inactive SLE patients as compared with inactive SLE patients.(3) The proportions of CD4+CD25highPD-1+Tr in SLE patients with nephritis were higher than those in patients without nephritis.But the percentage of CD4+ CD25 lowPD-1 + T cells was significantly decreased in SLE patients with nephritis as compared those without nephritis.(4)A positive correlation was observed for proportions of CD4+CD25highPD-1 + T cells with SLEDAI score.Proportions of CD4+ CD25high Tr,CD4+ CD25low PD-1 + T cells was inversely correlated with SLEDAI score.Conclusion The aberrations of proportions of CD4+CD25highpD-1+,CD4+CD25lowPD-1+,CD4+CD25high and CD4+CD25low T cells were observed in patients with SLE.The abnormality of PD-1 and PD-L1 pathway may play an important role in the function and number of Tr. 
 
Key words: 
Systemic lupus erythematosus;  Regulatory T cell ;  PD-1