Objective-To quantify the percentage of apoptotic peripheral blood neutrophils in systemic lupus erythematosus (SLE) and to determine the relations with disease activity and neutropenia. Methods-Neutrophil apoptosis in SLE patients (n =50) was assessed by flow cytometry using annexin V binding and fluorescent labelled anti-fas. Rheumatoid arthritis (RA, n =20) and inflammatory bowel disease patients (IBD, n =20) were studied as disease controls. Results-The percentage of apoptotic neutrophils, determined by annexin V binding, was increased in peripheral blood of SLE patients (median = 3.25%) compared with normal healthy donors (n =20, median = 1.20%) and disease controls (RA: median = 1.15%) (IBD: median =

ObjectiveTo investigate whether antidrug antibodies and/or drug non‐trough levels predict the long‐term treatment response in a large cohort of patients with rheumatoid arthritis (RA) treated with adalimumab or etanercept and to identify factors influencing antidrug antibody and drug levels to optimize future treatment decisions.MethodsA total of 331 patients from an observational prospective cohort were selected (160 patients treated with adalimumab and 171 treated with etanercept). Antidrug antibody levels were measured by radioimmunoassay, and drug levels were measured by enzyme‐linked immunosorbent assay in 835 serial serum samples obtained 3, 6, and 12 months after initiation of therapy. The association between antidrug antibodies and drug non‐trough levels and the treatment response (change in the Disease Activity Score in 28 joints) was evaluated.ResultsAmong patients who completed 12 months of followup, antidrug antibodies were detected in 24.8% of those receiving adalimumab (31 of 125) and in none of those receiving etanercept. At 3 months, antidrug antibody formation and low adalimumab levels were significant predictors of no response according to the European League Against Rheumatism (EULAR) criteria at 12 months (area under the receiver operating characteristic curve 0.71 [95% confidence interval (95% CI) 0.57, 0.85]). Antidrug antibody–positive patients received lower median dosages of methotrexate compared with antidrug antibody–negative patients (15 mg/week versus 20 mg/week; P = 0.01) and had a longer disease duration (14.0 versus 7.7 years; P = 0.03). The adalimumab level was the best predictor of change in the DAS28 at 12 months, after adjustment for confounders (regression coefficient 0.060 [95% CI 0.015, 0.10], P = 0.009). Etanercept levels were associated with the EULAR response at 12 months (regression coefficient 0.088 [95% CI 0.019, 0.16], P = 0.012); however, this difference was not significant after adjustment. A body mass index of ≥30 kg/m2 and poor adherence were associated with lower drug levels.ConclusionPharmacologic testing in anti–tumor necrosis factor–treated patients is clinically useful even in the absence of trough levels. At 3 months, antidrug antibodies and low adalimumab levels are significant predictors of no response according to the EULAR criteria at 12 months.

Lupus specific autoantigens are exposed on apoptotic cells. The increased number of apoptotic lymphocytes reported in systemic lupus erythematosus (SLE) may be attributable to abnormalities of lymphocyte Fas expression or serum soluble Fas. In the present study we analysed the count of circulating apoptotic lymphocytes in SLE patients (n=50), by flow cytometry using Annexin V, compared to rheumatoid arthritis patients (RA, n=20), inflammatory bowel disease patients (IBD, n=20) and normal controls (n=20). Lymphocyte Fas expression and serum soluble Fas were measured and related to numbers of apoptotic lymphocytes. The percentage of apoptotic lymphocytes, determined by Annexin V binding, was significantly increased in peripheral blood of SLE patients (median=4.2%) compared with normal healthy donors (median=1.1%) and IBD patients (median=2. 0%) but not RA (median=3.9%). SLE lymphocyte Fas expression was not significantly different from RA or IBD patients. Serum soluble Fas in SLE patients correlated positively with apoptotic lymphocytes and antibodies to double stranded DNA. This study suggests that increased apoptotic lymphocytes and increased lymphocyte Fas expression may not be specific to SLE. Serum soluble Fas may have a role in the regulation of lymphocyte apoptosis in SLE.