Background: Systemic Lupus Erythematosus (SLE) is a chronic inflammatory disorder affecting
multiple systems of the body. Clinical features show wide variations in patients with the different
ethnic background. Renal involvement is a predictor of poor prognosis. Immunological workup
is an integral part of SLE diagnostic criteria. Anti-ribosomal P Protein (anti-P) antibodies are highly
specific for SLE. They may be present in Antinuclear Antibodies (ANA) negative SLE patients. Their
role in Lupus Nephritis (LN) is under debate, some researchers found them associated with poor prognosis
whereas others found favorable effect of these antibodies on renal disease.
Objective: In this study, we investigated frequency of anti-P antibodies and the effect of these antibodies
on renal functions in the LN patients.
Methods: A total of 133 SLE patients were enrolled in this study. All patients had ANA in their sera.
Anti-P antibodies along with other autoantibodies against extractable nuclear antigens (anti-Sm, anti-
SS-A, anti-SS-B, anti-histones and anti-RNP) were detected by Immunoblot assay. Anti-dsDNA antibodies
were detected by indirect Immunofluorescence Assay (IFA).
Results: We found anti-P antibodies in 10.5% LN patients. Interestingly their presence in association
with anti-dsDNA was associated with improved renal functions in comparison to those who had antidsDNA
antibodies in isolation (serum creatinine: 1.3 ± 0.8 mg/dl vs. 3.0 ± 3.0; P= 0.091).
Conclusion: Anti-dsDNA antibodies are directly involved in renal pathology in SLE patients. As these
antibodies are nephrotoxic, concomitant occurrence of anti-P antibodies seems to offer a shielding
effect on renal functions, which was evident by normal serum creatinine levels. Therefore, anti-P antibodies
may be considered as a good prognostic marker in these patients.