Interkit Reproducibility of the Indirect Immunofluorescence Assay on HEp-2 Cells Depends on the Immunofluorescence Reactivity Intensity and Pattern.

Introduction: The indirect immunofluorescence assay on HEp-2 cells (HEp-2/IFA) is used worldwide for screening for autoantibodies to cellular antigens. Cell culture and fixation methods influence the cell distribution of autoantigens and the preservation of epitopes. Therefore, discrepancy of results obtained using different HEp-2/IFA kits (interkit nonreproducibility) is a common phenomenon in the clinical laboratory routine. Objective: This study evaluated the interkit nonreproducibility of HEp-2/IFA results using samples from patients with systemic autoimmune disease (SAD), nonautoimmune diseases (NAD), and healthy blood donors (HBD). Methods: Serum from 275 SAD patients, 293 NAD patients, and 300 HBD were processed at 1:80 dilution using four HEp-2 kits according to the manufacturers' instructions. Interkit reproducibility was determined for positive/negative results and patterns. The agreement of positive/negative results among kits for each sample was determined as the reactivity agreement score (RAS). The pattern reproducibility score (PRS) in each sample was calculated as a function of the number of kits showing equivalent patterns. Qualitative variables and ordinal variables were analyzed by the Chi-square and Mann-Whitney U tests, respectively. Results: A total of 402 samples were nonreactive in all kits and were considered devoid of autoantibodies. Further analysis included the 466 reactive samples (238 SAD, 119 NAD, 109 HBD). Reactivity to the nucleus had the highest interkit reproducibility (RAS = 83.6), followed by the metaphase plate (RAS = 78.9), cytoplasm (RAS = 77.4), and nucleolus (RAS = 72.4). Interkit reproducibility was higher in SAD (RAS = 78.0) than in NAD (RAS = 70.6) and HBD (RAS = 71.3) groups. Samples with strong reactivity (++++/4 and +++/4) had higher interkit reproducibility than those with weak reactivity (+/4). In the SAD group, RAS for nuclear reactivity was 87.5% for strongly reactive samples as opposed to 4.4% for weakly reactive samples, and the same was observed for NAD and HBD samples. The most robust patterns were the centromere AC-3 (PRS = 78.4), multiple nuclear dots AC-6 (PRS = 73.6), nuclear coarse speckled AC-5 (PRS = 71.3), nuclear homogeneous AC-1 (PRS = 67.9), and the reticular cytoplasmic AC-21 (PRS = 68.6). Conclusion: Interkit nonreproducibility in HEp-2/IFA is prevalent and occurs with the highest frequency with weakly reactive samples. International initiatives with the engagement of in vitro diagnostic industry are encouraged to promote the harmonization of the properties and performance of HEp-2/IFA commercial kits.

Leflunomide in Takayasu arteritis - A long term observational study.

OBJECTIVE: To evaluate the extended follow-up data on efficacy and toxicity of leflunomide therapy in Takayasu arteritis (TA) patients previously enrolled in the original open-label study of short-term effects of leflunomide in TA. METHODS: An open-label long-term longitudinal study was performed in TA patients who fulfilled the 1990 American College of Rheumatology criteria for TA and had participated in a previous study that evaluated short-term efficacy of leflunomide in TA. Complete follow-up information could be retrieved from 12 out of 15 patients enrolled in the original study. Disease activity was evaluated by Kerr's criteria and by the Indian Takayasu Activity Score 2010 (ITAS2010). RESULTS: The mean follow up time was 43.0±7.6 months and 5 (41.6%) TA patients remained on leflunomide therapy while 7 (58.3%) TA patients had to change to another therapy due to failure to prevent relapses in 6 patients and toxicity in one patient. No significant differences were found between patients who remained on leflunomide therapy and those who changed to another agent regarding age at study entry, time since diagnosis, prednisone daily dose at study entry, baseline ITAS2010, mean or maximum ESR and CRP, and cumulative prednisone dose at study end. Among TA patients who had changed leflunomide to another agent, two had an additional clinical relapse and needed to change therapy. CONCLUSION: Leflunomide led to sustained remission in approximately half of patients at a mean time of 12 months and was well tolerated by TA patients.

Leflunomide in Takayasu arteritis - A long term observational study. / Leflunomida na arterite de Takayasu - Estudo observacional de longo prazo.

OBJECTIVE: To evaluate the extended follow-up data on efficacy and toxicity of leflunomide therapy in Takayasu arteritis (TA) patients previously enrolled in the original open-label study of short-term effects of leflunomide in TA. METHODS: An open-label long-term longitudinal study was performed in TA patients who fulfilled the 1990 American College of Rheumatology criteria for TA and had participated in a previous study that evaluated short-term efficacy of leflunomide in TA. Complete follow-up information could be retrieved from 12 out of 15 patients enrolled in the original study. Disease activity was evaluated by Kerr's criteria and by the Indian Takayasu Activity Score 2010 (ITAS2010). RESULTS: The mean follow up time was 43.0±7.6 months and 5 (41.6%) TA patients remained on leflunomide therapy while 7 (58.3%) TA patients had to change to another therapy due to failure to prevent relapses in 6 patients and toxicity in one patient. No significant differences were found between patients who remained on leflunomide therapy and those who changed to another agent regarding age at study entry, time since diagnosis, prednisone daily dose at study entry, baseline ITAS2010, mean or maximum ESR and CRP, and cumulative prednisone dose at study end. Among two TA patients who had changed laflunomide to another agent, two had a clinical relapse and needed to change therapy. CONCLUSION: Leflunomide led to sustained remission in approximately half of patients at a mean time of 12 months and was well tolerated by TA patients.