狼疮肾炎患者血清和肾组织IgG4检测及其与疾病活动指标的相关性分析

Correlation of serum level and glomerular deposition of IgG4 with disease activity parameters in lupus nephritis patients

探讨狼疮肾炎(lupus nephritis,LN)患者血清IgG4水平和肾脏IgG4沉积情况与疾病活动指标的相关性,初步明确IgG4在LN发病中的作用,为LN的防治提供新的线索。入组LN患者146例(WHO分型包括II型18例,IV型86例,V型9例,V+IV型33例),并以70例正常人为对照;酶联免疫吸附试验(ELISA)检测血清IgG4水平,并分析其与临床指标(血肌酐、总胆固醇、血尿素氮、血清白蛋白、血尿酸和24h尿蛋白等)的相关性;直接免疫荧光法检测LN患者肾脏组织IgG各亚型(IgG1、2、3和4)的沉积情况。结果显示:LN患者血清IgG4水平较正常人显著升高(P<0.05);LN患者血清IgG4水平与血肌酐、总胆固醇和24h尿蛋白定量呈负相关(r=0.24,P<0.05;r=0.35,P<0.05;r=0.28,P<0.05),与血清白蛋白水平呈正相关(r=0.22,P<0.05),但与血尿素氮、血尿酸无相关。IgG及其亚型在LN组织中沉积普遍,以毛细血管壁和系膜区为主。其中IV、V、(V+IV)型IgG1、IgG2和IgG3的沉积强度显著强于II型;V型IgG4沉积强度显著强于IV(P<0.05);IV型LN组织沉积IgG1/IgG4的比值显著高于V型(P<0.05);V型LN组织沉积IgG4/总IgG的比值显著高于IV型(P<0.05)。IgG4在LN的发病中可能起保护作用,有望为LN的防治提供新的策略。

We determined serum levels and glomerular deposition of IgG4 and analyzed the correlations of IgG4 with disease ac- tivity parameters in patients with lupus nephritis （LN）, in order to clarify the role of IgG4 in the development of LN, and pro- vide new clues for diagnosis and therapy of LN. One hundred and forty-six patients with LN （class II, 18; class IV, 86; class V, 9; class Vq- IV, 33） were recruited in this study. ELISA methods were employed to detect the total serum levels of IgG4 and its correlations with the following clinical parameters were analyzed among them including serum creatinine （Scr）, choles- terol （CHOL）, blood urea nitrogen （BUN）, serum albumin, serum uric acid （SUA）, 24 hour urinary proteins et al.. Immu- nofluorescence were employed to detect the deposition of the subclasses of IgGs including IgG1, IgG2, IgG3 and IgG4 in the re nal tissues of LN patients. The results showed that serum levels of IgG4 was significantly higher than those in the normal con- trois （P〈0.05）, were negatively correlated with serum creatinine （Scr）, cholesterol （CHOIr） and 24 hours urinary protein （r =0.24, P〈0.05; r=0.35, P〈0.05 and r=0.28, P〈0.05; respectively）, and positively associated with serum albumin （r =0.22, P〈0. 05）. There was no correlation between serum levels of IgG4 and blood urea nitrogen （BUN）, as well as serum uric acid （SUA）. Deposition of IgG1, IgG2, IgG3 and IgG4 were found mainly in the capillary walls and mesangial areas of LN. Also, the deposition of IgG1, IgG2 and IgG3 in class IV, V, V＋ IV were significantly higher than those in class II, how ever, the deposition of IgG4 in class V were significantly higher than those in IV （P〈0.05）, also the ratio of MFI of IgG1 to IgG4 deposition in class IV was significantly higher than that in class V （P〈0.05）, and the ratio of MFI of IgG4 to total IgGs deposition in class V was significantly higher than that in class IV （P〈0.05）. Taken together, IgG4 may play a protective role in lupus nephritis and may provide new clues for the target therapy for SLE.