Objective: To assess circulating follicular helper T (Tfh)–like CD4+ T cells in patients with systemic lupus erythematosus (SLE) and determine their relationship to disease activity.Methods: Blood samples from patients with SLE, as well as blood samples from patients with Behçet's disease (BD) and healthy individuals as controls, were analyzed. In all samples, circulating Tfh‐like cells were enumerated by flow cytometry, using, as markers, expression of CXCR5, inducible T cell costimulator (ICOS), and programmed death 1 (PD‐1) protein, as well as secretion of interleukin‐21 (IL‐21). The frequency of circulating Tfh‐like cells was compared to that of circulating plasmablasts (CD19+IgD−CD38+). In addition, the possible association of circulating Tfh‐like cells with the SLE Disease Activity Index (SLEDAI) was evaluated.Results: The subset of circulating Tfh‐like T cells, identified as CXCR5^highICOS^highPD‐1^high, was expanded in the blood of SLE patients compared to controls. Circulating Tfh‐like cells were found to produce IL‐21 and had lower expression of CCR7 as compared to that in circulating CXCR5^high central memory T cells, thereby enabling their distinction. Expression of PD‐1, but not ICOS or CXCR5, was significantly elevated in circulating Tfh‐like cells from SLE patients compared to controls. PD‐1 expression among CXCR5^high circulating Tfh‐like cells correlated with the SLEDAI, frequency of circulating plasmablasts, and anti–double‐stranded DNA antibody positivity, but not with disease duration or past organ injury; rather, this cell profile appeared to be a reflection of current active disease.Conclusion: Circulating Tfh‐like cells are associated with disease activity in SLE, suggesting that their presence indicates abnormal homeostasis of T cell–B cell collaboration, with a causal relationship that is central to disease pathogenesis. These findings also suggest that circulating Tfh‐like cells provide a surrogate for aberrant germinal center activity in SLE, and that their PD‐1 expression offers a tool for measuring disease activity and monitoring the response to therapies.

Defective regulation of apoptosis may play a role in the development of autoimmune diseases. Fas and Bcl-2 proteins are involved in the control of apoptosis. The aims of this study were to determine the expression of Fas antigen and Bcl-2 protein on peripheral blood T and B lymphocytes from patients with juvenile-onset systemic lupus erythematosus (JSLE), juvenile rheumatoid arthritis (JRA) and juvenile dermatomyositis (JDM). Thirty-eight patients with JSLE, 19 patients with JRA, 10 patients with JDM and 25 healthy controls entered the study. Freshly isolated peripheral blood mononuclear cells (PBMC) were stained for lymphocyte markers CD3, CD4, CD8, CD19 and for Fas and Bcl-2 molecules. Expressions were measured by three-color flow cytometry. Statistical analysis was performed using Kruskal–Wallis test. Percentages of freshly isolated T lymphocytes positively stained for Fas protein from JSLE patients were significantly increased compared to healthy controls, patients with JRA and patients with JDM. Percentages of B lymphocytes positive for Fas from JSLE patients were higher than healthy controls and JRA patients. In addition, Fas expression on T cells from patients with JRA was increased compared to JDM patients. Otherwise, Fas expression on T and B cells from JRA and JDM patients were similar to healthy controls. MFI of Bcl-2 positive T lymphocytes from JSLE patients were significantly increased compared to healthy controls and JRA patients. MFI of Bcl-2 protein on B lymphocytes from JSLE patients was similar to healthy controls and patients with JRA and JDM. Bcl-2 expression did not differ between JRA and JDM patients and healthy controls. In conclusion, increased expression of Fas and Bcl-2 proteins observed in circulating T and B lymphocytes from patients with JSLE, but not from patients with JRA and JDM, suggests that abnormalities of apoptosis may be related to the pathogenesis of JSLE and probably are not a result of chronic inflammation.