Serum Anti-Immunoglobulin Binding Protein in Rheumatoid Arthritis and Systemic Lupus Erythematosus: Role in Diagnosis and Disease Activity

Background: Serum Anti-Immunoglobulin Binding Protein (Anti-BiP) antibodies may be associated with disease activity among rheumatoid arthritis (RA) as well as Systemic Lupus Erythematosus (SLE) patients. This research aim was assessment of possible role of serum Ant-BiP in diagnosing RA as well as SLE to find serum Ant-BiP correlation with disease activity. Methods: This case-control study comprised 78 participants categorized as follows: Group I involved 26 cases with RA, Group II comprised 26 SLE Patients, Group III involved 26 apparently healthy individuals as control group. All of them underwent laboratory investigations, serum Anti-BiP using enzyme-linked immunosorbent assay. Results: Serum anti-BiP level was significantly higher among RA, SLE patients than controls (P<0.001). Among RA patients, DAS28 showed statistically significant positive correlations with serum anti-BiP (r=0.443, P=0.023), anti-CCP (r=0.538, P=0.005), ESR (r=0.667, P<0.001). Among SLE group, SLE-DAS showed statistically significant positive correlations with disease duration (r=0.423, P=0.031), ESR (r=0.398, P=0.044), serum anti-BiP (r=0.634, P<0.001). ROC analysis demonstrated that anti-BiP effectively differentiated patients from controls, with 80.77% sensitivity 73.08% specificity at a cutoff of 6.15 ng/ml (AUC: 0.832). It distinguished active disease from remission in SLE with 86.36% sensitivity 75% specificity (cutoff: 7 ng/ml, AUC: 0.909) active disease from remission in RA with 77.27% sensitivity 100% specificity (cutoff: 7.35 ng/ml, AUC: 0.886). Conclusion: Combined use of ant BiP antibodies with RF /or ACPAs would be helpful for diagnosis of RA. Anti BiP antibodies as a biomarker showed significant high sensitivity specificity in assessment of RA disease activity in addition to the SLE disease activity