Significance of antibodies to ribosomal P proteins in lupus nephritis patients and their relation to disease activity: clinical and laboratory study

Abstract

Background Lupus nephritis (LN) is a prominent feature in systemic lupus erythematosus (SLE), present in 15–30% of patients with lupus at the time of the initial diagnosis and in 30–50% during the disease progression. Objectives The aim of this study was to determine the significance of anti-ribosomal P protein (anti-P) antibodies and LN and their relation to disease activity and other SLE manifestations. Patients and methods Fifty active LN patients were subjected to full clinical examination (assessment of SLE disease activity using the systemic lupus erythematosus disease activity index and assessment of SLE disease severity using Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index), routine laboratory investigations, anti-dsDNA antibodies, and anti-P antibodies. Results Comparison between the data of LN in both groups (anti-P positive/anti-dsDNA negative and anti-P negative) shows that there was a statistically significant difference in age (P=0.042), hypertension (P=0.00), and psychiatric manifestations (P=0.004). On comparison of both groups as regards vasculitis, there was a borderline statistical significance (P=0.050). Comparison of both groups as regards creatinine level or biopsy class V showed a statistically significant difference with a higher percentage in the anti-P positive/anti-dsDNA negative group (P=0.024 and 0.040, respectively). Conclusion Anti-P antibody-positive patients have younger ages, lower creatinine level, lower incidence of hypertension, usually class V in renal biopsy, but more susceptible to have psychiatric manifestations compared with anti-P antibody negative patients.

Keywords

• anti-ribosomal P protein antibody
• enzyme-linked immunosorbent assay
• lupus nephritis
• systemic lupus erythematosus