Anti-ribosomal P protein antibodies

Abstract

Anti-ribosomal P protein antibodies (Abs) recognize three specific ribosomal proteins located in the large ribosome's subunit. The term anti-ribosomal P protein Abs, often shortened in anti-P Abs, is due to the fact that these three proteins, P0, P1 and P2, of 38, 19 and 17 Kd molecular weight, respectively, are phosphorylated. One of the major points of interest of these autoAbs derives from their high specificity for systemic lupus erythematosus (SLE), their description in other connective tissue diseases (CTDs) being only occasional. In SLE patients, their association with renal and hepatic involvement has been proposed, while the possible association with psychiatric and/or neurological involvement is still a matter of debate. From a serological point of view, a preferential association of anti-P with anti-Sm and/or anti-DNA Abs, possibly due, at least in part, to cross-reactivity, has been suggested. This observation is intriguing since all these autoAbs are considered specific serological indicators of SLE. This review will summarize clinical and serological data on anti-P Abs provided by the main studies published in the last few years and the more recent findings about proteins constituting their targets.

International Multicenter Evaluation of Autoantibodies to Ribosomal P Proteins

“…Several studies have shown that both the acidic and hydrophobic clusters, but not the phosphorylation of the P proteins, are critical for autoantibody binding (8,16,23). Furthermore, epitope mapping studies have shown that the major epitope domain is located within the last six C-terminal amino acids (GFGLFD) (8,16,23).The reported prevalence of anti-Rib-P antibodies in SLE ranges from 10 to 40%, being higher in Asian patients and at a relatively lower prevalence in black and Caucasian patients (3,12,15,18,23,30,35). The variation in the observed frequency may be related to a number of factors but is dependent in large part on the test system used to detect the autoantibodies.…”

“…Anti-Rib-P antibodies were mainly detected in patients during the active phase of SLE and were believed to be correlated with lupus nephritis or hepatitis (4,11,12,24,28,30,36).…”

“…The reported prevalence of anti-Rib-P antibodies in SLE ranges from 10 to 40%, being higher in Asian patients and at a relatively lower prevalence in black and Caucasian patients (3,12,15,18,23,30,35). The variation in the observed frequency may be related to a number of factors but is dependent in large part on the test system used to detect the autoantibodies.…”

“…The antigenic analytes employed in these tests included purified native proteins, recombinant polypeptides, a synthetic peptide comprising the 22 C-terminal amino acids (C22), and a multiple antigen peptide construct (1,12,13,21,22,23,26,30,38). Recently, a Rib-P profile assay based on the three recombinant ribosomal P proteins and the C22 peptide in separate tests was developed and evaluated (22).Anti-Rib-P antibodies were mainly detected in patients during the active phase of SLE and were believed to be correlated with lupus nephritis or hepatitis (4,11,12,24,28,30,36). …”

Antibodies directed against ribosomal P proteins cross-react with phospholipids

“…Subsequent studies, however, did not confirm these observations and this relationship is still a matter of debate [2,3,11,12]. Anti-P antibodies were also related to renal involvement in SLE patients such as anti-dsDNA [13,14].…”