Anti Cathepsin Antibody In Systemic Lupus Erythematosus


Abstract:Antineutrophil cytoplasmic autoantibodies (ANCA) were found in patients withsystemic lupus erythematosus (SLE). Cathepsin G was the major target antigen. However,some ANCA-positive sera did not recognize either of them.The present study was toinvestigate the unknown target antigens of ANCA (Cathepsin G) in patients with SLE and itsrelation to the activity of the disease (ds DNA ),C1q ,C3and C4.Seventy four SLE patients referred to immunological department in teachinglaboratory medical city during period of (1st of march–31st of May) 2011 and 30 apparentlyhealthy individual as a control group were subjected to Antinuclear antibody (ANA),Cathepsin G and C1q were detected by enzyme-linked immunosorbent assay (ELISA)technique.While dsDNA was detected by indirect immunofluorescent (IIF) technique and C3,C4 by single radial immunodiffusion (SRID).The age of SLE patients ranged between (4-71) years with mean age of 32.4. Themean C1q and Cathepsin G levels were 30.14 and 9.7 respectively with significant differenceif compare it with the healthy control group. A significant result found between mean age ofSLE patients and Cathepsin Ab of a P value 0.007.The Cathepsin G antibody was found in 26 (35%) of SLE patients with a significant Pvalue (0.0001).The Cathepsin Ab were detected in 18 (43.9%) of a patients with positive ds DNAwith no significant P value 0.078. while C1q Ab were detected in 38 (51.4%) of SLE patientsand only 18 (47.4%) from them with Cathepsin Ab with statistically significant P value 0.024.Cathepsin Ab found in 19 (42.2%) of SLE patients with low level of C3 and only 6 (21.4%)of normal level of C3 with no significant P value0.076.This study showed 54(73.0%) of SLE patients had low level of C4 with no significantP value (0.15) and the Cathepsin Ab detected in 22 (40.7%) of them with no statisticallysignificant P value 0.097.A statistically significant result were found for ANA, C1q,C3,C4 and Cathepsin Abif we compare the result of SLE patients with control group, while The Cathepsin G antibodywas found statistically significant in SLE patients ,with significant relation to C1q,on otherhand no relation found with the activity of the disease (ds DNA ),C3 and C4 levels.Key Word: SLE, Cathepsin G, ds DNA, C1q, C3, C4