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Objective: To evaluate the frequency of cell‐bound complement activation products (CB‐CAPs) as a marker of complement activation in patients with suspected systemic lupus erythematosus (SLE) and the usefulness of this biomarker as a predictor of the evolution of probable SLE into SLE as classified by the American College of Rheumatology (ACR) criteria. Methods: Patients in whom SLE was suspected by lupus experts and who fulfilled 3 ACR classification criteria for SLE (probable SLE) were enrolled, along with patients with established SLE as classified by both the ACR and the Systemic Lupus International Collaborating Clinics (SLICC) criteria, patients with primary Sjögren's syndrome (SS), and patients with other rheumatic diseases. Individual CB‐CAPs were measured by flow cytometry, and positivity rates were compared to those of commonly assessed biomarkers, including serum complement proteins (C3 and C4) and autoantibodies. The frequency of a positive multianalyte assay panel (MAP), which includes CB‐CAPs, was also evaluated. Probable SLE cases were followed up prospectively. Results: The 92 patients with probable SLE were diagnosed more recently than the 53 patients with established SLE, and their use of antirheumatic medications was lower. At the enrollment visit, more patients with probable SLE were positive for CB‐CAPs (28%) or MAP (40%) than had low complement levels (9%) (P = 0.0001 for each). In probable SLE, MAP scores of >0.8 at enrollment predicted fulfillment of a fourth ACR criterion within 18 months (hazard ratio 3.11, P < 0.01). Conclusion: Complement activation occurs in some patients with probable SLE and can be detected with higher frequency by evaluating CB‐CAPs and MAP than by assessing traditional serum complement protein levels. A MAP score above 0.8 predicts transition to classifiable SLE according to ACR criteria. [ABSTRACT FROM AUTHOR]

Objective Neonatal lupus (NL) occurs in fetuses exposed to maternal anti-SSA/Ro and/or anti-SSB/La antibodies, although the mothers themselves may not manifest any clinical disease. A focus on transmission of risk factors for NL from maternal grandparents to mothers of children with NL may yield dividends toward understanding the aggregation of autoantibodies and genetic factors in affected families. This study was perforned to determine the role of maternal grandparents in the development of the autoimmune phenotype of mothers of children with NL. Methods Fifty-one mothers of children with cardiac and/or cutaneous NL, 48 maternal grandmothers, and 35 maternal grandfathers in the Research Registry for Neonatal Lupus were interrogated for clinical symptoms by questionnaire and underwent laboratory assessments, including determination of anti-SSA/Ro and anti-SSB/La antibody status (by enzyme-linked immunosorbent assay) and genotype at rs1800629 ( TNFα) and rs7775397 ( C6orf10) (allelic discrimination). The transmission disequilibrium test (TDT) was computed to test for nonrandom transmission from maternal grandparents to mothers of children with NL. Results The common phenotypic feature in mothers of children with NL was the autoantibody and not the clinical profile; 7 had lupus, 14 had Sjögren's syndrome, 7 had both, and 23 were asymptomatic. Mothers of children with NL were significantly enriched for the risk alleles at both TNFα and C6orf10. The grandparents of children with NL carried minimal burden for autoimmune disease or abnormal antibody production and were not enriched in the genetic risk factors. However, the TDT analysis showed significant excess transmission of the risk alleles at both TNFα (odds ratio [OR] 6.67, P = 3.93 × 10−4) and C6orf10 (OR 35.0, P = 3.74 × 10−5) to mothers of children with NL. Conclusion Mothers of children with NL are enriched for the TNFα and C6orf10 risk alleles, which are preferentially inherited from the asymptomatic maternal grandparents. These findings support the hypothesis that the development of NL and genetic etiology are multigenerational. [ABSTRACT FROM AUTHOR]