Protective Role Of Anti-Ribosomal P Antibody In Patients With Lupus Nephritis

Aim The aim of this study was to define clinical, histopathologic, and prognostic differences according to the presence of anti-ribosomal P antibody (anti-P) in Korean patients with biopsy-proven lupus nephritis (LN). Methods We studied 79 patients who underwent kidney biopsies prior to the start of induction treatment, and who were subsequently treated with immunosuppressive drugs for at least 6 months and followed-up for more than 6 months. Anti-P was measured by immunoblot analysis at the time of renal biopsy. Results Of all patients, 35.4% were anti-P-positive. Such patients exhibited earlier LN onset, a higher Systemic Lupus Erythematosus Disease Activity Index 2000 score, and a higher estimated glomerular filtration rate at the time of renal biopsy, than did those without antibodies. Upon renal histopathological analysis, patients with anti-P exhibited less interstitial inflammation in terms of the activity index, less glomerular sclerosis, less tubular atrophy, and less interstitial fibrosis in terms of the chronicity index. Furthermore, anti-P was associated with lower chronicity scores. At a median follow-up time of 47 months, renal function was preserved in 27 of 28 patients who had anti-P, but only 38 of 51 patients without such antibodies did not progress to chronic renal disease. After multivariate logistic regression, we found that anti-P positivity was associated with a reduced rate of progression to chronic kidney disease after adjusting for gender, baseline creatinine, activity and chronicity score, and treatment response (odds ratio = 0.196, 95% CI: 0.039-0.989, P = 0.048). Conclusion Anti-P was associated with better histological findings, and anti-P-positive patients had better renal outcomes than those without anti-P.