Establish A Sandwich ELISA System To Examine Serum IgG4Levels And Investigate The Roles Of SMSs On The Pathogenesis Of SLE

Serum IgG4Levels Detected by an Established ELISA Systemand Its Clinical Applications in Autoimmune DiseasesObjective This study is to establish a sandwich-ELISA (enzyme-linked immunosorbentassay) method which can detect human serum IgG4concentration specifically andsensitively. Measure the serum IgG4levels using this established ELISA in differentautoimmune diseases including Systemic Lupus Erythematosus (SLE), Sjogren’s Syndrome(SS), Dermatomyositis or Polymyositis (DM/PM) and IgG4-RD.Methods Through coating anti-IgG4monoclonal antibodies on the ELISA plates weestablished an ELISA system using human IgG4standard antibody as standard curve.Toevaluate the reliability of this ELISA system, we sent10serum specimens to KanazawaMedical University (Japan,using Binding Site kit) and compared their results with ours. Bythis method, we measured serum IgG4levels of53healthy controls,103patients withSystemic Lupus Erythematosus (SLE),41patients with Sjogren’s Syndrome (SS),21patients with Dermatomyositis or Polymyositis (DM/PM) and2cases who were suspectedas IgG4-related disease. Single factor analysis of variance was used for the statisticalanalysis.Results This established ELISA system discovered high sensitivity and specificity inmeasuring serum IgG4levels. We found that serum IgG4levels in normal control, SLE, SSand DM patients were0.23±0.16g/L；0.16±0.15g/L；0.22±0.18g/L and0.40±0.32g/Lrespectively. No significant difference was observed among these groups (P＞0.05). Theresults from two labs revealed reliable consistence with each other. The serum IgG4levels of two suspected cases were1.63g/L and4.65g/L respectively, and both decreasedmarkedly after treatment with glucocorticoids.Conclusion This established ELISA system can be used for detection of serum IgG4levels correctly and sensitively. Because of its low cost and easy accessibility, werecommend this method to clinical examination for diagnosis of IgG4related disease, as well as observation of curative effect. Elevated serum IgG4levels assist in diagnosis ofIgG4-RD and observation of curative effect in IgG4-RD, but not in other autoimmunediseases. The roles of SMSs on the pathogenesis of SLEObjective This study was designed to measure the expression levels ofSMSs(sphingomyelin synase) in peripheral blood monouclear cells(PBMC) from patientswith SLE,aimed in finding experimental evidences for its possible mechanism.Methods33SLE patients diagnosed in our department between2011-2012and20normalcontrols participated in this study.10ml peripheral blood was collected from each personand the mononuclear cells were extracted using ficoll according to the manufacturer’sprotocol. Total RNA was isolated and the qualified RNA was reverse transcribed tocDNA,followed by determining the expression levels of SMS1/SMS2through real timePCR. Group T test was used in this study and p<0.05was considered statisticallysignificance.Results There were significant differences in SMS1and SMS2expression levels in SLEpatients compared with healty controls, with the mean value of ΔCt1(Ct(SMS1)-Ct(GAPDH))andΔCt2(Ct(SMS2)-Ct(GAPDH)) of SLE patients were5.86±1.21and12.64±2.0respectively,while the correspondence value in healthy controls were6.6±0.625and13.84±1.2respectively. The differences were statistically significant(p<0.05).conclusion Both SMS1and SMS2were highly expressed in SLE patients than in normalcontrols,which may elevate PBMC activities in SLE patients and thus lead to immunedisorders. Therefore,we proposed that raised SMSs expression may play roles inlymphocytes hyperfunction through SMSs-SM-lipid raft axle and may be identified as anovel target for SLE diagnosis and therapy.