| IntroduetionThe function of erythrocytes is to transport oxygen to tissue,and support the normal physiological function of human body as previously known. Amount of studies in recent years have found that erythrocytes in primate carries multiple and enhanced immunological functions. As early as 1930, Duke et al observed that Trypanosoma brucei could bind to primate erythrocytes with specific antiserum and complement in vivo.In 1953,Nelson observed that specifcally opsonized treponemes and pneumococci could adhere to human erythrocytes. In 1979,Fearon purified the glycoprotein which could bind to humam erythrocytes.And in late studies he identifed this glycoprotein(CRl) on erythrocytes,pol Ymorp-honuclear leukocytes,monocytes,B lymphocytes,glomerular epithelial cells and follicular dentric cells.The E-CR1 has a lot of physioligical functions. (1) As the decay factor of trasverase C3bBbP, E-CR1s suppress complement activation in both classic and altenative pathways, protect invasion and damage from complement. (2) To transport opsonized immune complexes in circulation to liver and spleen. The immune compnexes are then deleted in liver and spleen. (3) As cofactor of factor H helps the cleavage of c3b by facfor I. And as the only cofactor of factorI,E-CR1s help to cleave C3b to C3c and C3dg. (4) To activate phagocytosis of immune complexes by neutrophils and monocytes mediated by C3b, induce IL-1 secretion of monocytes, enhance B cell differentiation.Systemic lupus erythematosus (SLE) is an non-organ specific autoimmune disease. Its pathogenic mechinasm includes cell immune, humoral immune, complement system and cytokines. Increased immune complexs was detected im active SLE. The elevated immune complexs could deposit on organs and tissues, induce and enhance autoimmune injuries. Anthony et al and Angelo et al found that level of E-CR1 had a linear negative correlation with level of anticardiolipin antibodies, positive correlation with level of C4d/C3d on erythrocytes and level of serum complement CH50 in patients with active SLE. But by now there are no study reports about correlation between E-CR1 level and SLE disease activity.ObjectivesTo study correlationship between E-CR1 and SLE disease activity in patients with SLE using FACS, and to explore a new method in the field of pathogenesis and disease monitors in SLE.Materials and Methods1. Study objects72 cases of patients fullfilled 1982 SLE classification criteria by ARA were included. Twenty heathy cases were selected as control. The two groups matched with each other in sex and age.2.ExperimeSnt equipments and ReageantsFlow cytometer (FACS can, produced by Becton-Dickinson company, America), cryogenic centrifugal apparatus (produced by Japanese HITACHI company). Biotin labelled mouse anti human CD35 monoclonal anitbody (Ancell company, America), PE labelled streptavidin (eBioscient company, America). 3 Experiment methods:(1)CD35/Biotin (1.0mg/ml) was diluted at 1:160 folds, streptavidin-PE(250ng/ml) was diluted at 1:25 folds. 3ml heparin anti-coagulated blood was obtained from elbow venous in the morning. Then 10ul blood was diluted in 2ml 1% bovine PBS, centrifugated at 1000rs/min for 4mins. The dilution and centrifugation was total about three times.After three times, the deposits was added 100ml 1% bovine PBS, then control tube and experiment tube was added 100ul diluted erythrocytes, respectively. Then 10ul antiCD35/Biotin was added into the experiment tube,the reaction was about 30mins at room tempratures protecting from light. 30 mins later, dilution and centrifugation was done for three times,then 10ul streptavidin-PE was added into experiment tube, and the reaction was about 20mins at room tempratures protecting from light. After three times dilution and centrifugation, the erythrocytes were detected by flow cytometer. "door technique" to mark off erythrocythes was used, each standard 10000cells was set. The results were analysed through "Cell Ques plot" software. The average fluorescence intensity of E-CR1 was recorded. (2) Serum complement C3,C4 and erythrocyte sedimentation rates were detected at the same time as a routine test by our clinical laboratory. (3) Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), The Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index for Systemic Lupus Erythematosus (SLICC/ACR Damage Index for SLE, abbrevieted as SLEDI) and Systemis Lupus Activity Measure (SLAM) scoring instruments were used to assess disease activity. (4) The data was analysed through SPSS12.0 software.Results1 E-CR1 levels in SLE group compared with that in control group: E-CR1 in SLE group was 20.25±9.15, E-CR1 in control group was 57.00±10.41, P<0.01.2 The E-CR1 in SLE group shows a significant negative linear correlation with SLAM(P=0.005), and a negative linear correlation with ESR (P=0.01),and no correlationship with SLEDAI,SLEDI and complement C3and C4 (P>0.05).Conclusion1 The E-CR1 in SLE group is significantly lower then that in control group.2 E-CR1 has a significant negative linear correlation with SLAM, a negative linear correlation with ESR. E-CR1 could be used as one of biomarkers to assess disease activity in patients with SLE.3 E-CR1 shows no correlation with SLEDAI, SLEDI and complement C3 and C4.
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