Background Autoantibodies to ribosomal-P protein (anti-P antibodies) are predominantly found in sera of patients with systemic lupus erythematosus (SLE) and have been correlated with neuropsychiatric lupus in some but not all studies.1 The frequency of anti-P antibodies in SLE population can vary from 6% to 36% in different ethnic groups.2
Objectives To clarify the frequency of presence of anti-P antibodies in patients with SLE.
Methods The investigated group constituted of 36 SLE patients (age 21–52 years, SLE duration 0.5–16 years), sera from 5 patients with discoid lupus and 48 RA patients were tested too. Sera of 20 normal healthy persons were used as normal controls. Anti-P antibodies were measured by immunoblot (INNO™ANA, Innogenetics, Belgium) and ELISA (ABP Diagnostics Inc., Canada) using commercial kits.
Results Anti-P antibodies were found in 5/36 (13.9%) SEL patients, using immunoblot, and in 7/36 (19.4%) SEL patients, using ELISA, and in 1/48 RA patient (2.1%) using ELISA. None of the sera of the other RA patients as well as discoid patients and normal persons was found to be positive for anti-P antibodies. Anti-P antibodies were occurred together with ANA, dsDNA and histone antibodies (p < 0.0001). No clinical differences were found in patients with anti-P antibodies, belonging anti-SmB and anti-SmD positive and negative groups. Among the investigated patients neurological disorders were seen only in two patients, while no studied patient had lupus psychosis. One patient had encephalomeningitis (positive anti-P antibodies by both methods) the other had APS with thrombosis (positive anti-P antibodies by ELISA). In our study all SLE patients with anti-P antibodies had active lupus nephritis (p < 0.0001), LE cells (p < 0.0001) and cardiac disorders (p > 0.05). The majority (6 from 7 patients) of these patients had polyarthritis. None of the patients with SLE duration less than 3 years had anti-P antibodies. Disease duration was longer in patients positive for anti-P antibodies (4.30 ± 5.03 and 10.10 ± 6.05 years, accordingly; p < 0.043).
Conclusion The clinical significance of presence of anti-P antibodies in SLE is limited. Presence of these antibodies is associated with acute lupus nephritis; the antibodies are found in patients with long disease duration.
Teh L-S, Isenberg DA. Antiribosomal P protein antibodies in systemic lupus erythematosus. A reappraisal. Arthritis Rheum. 1994;37:307–15
Arnett FC, Reveille JD, Moutsopoulos HM, Georgesen L, Elkon KB. Ribosomal P antibodies in systemic lupus erythematosus. Arthritis Rheum. 1996;39:1833–9
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