Antibodies directed against ribosomal P proteins cross-react with phospholipids.
Anti-ribosomal P protein (anti-P) antibodies are marker antibodies in systemic lupus erythematosus (SLE). Their association with psychiatric or neurological manifestations has been proposed, but remains controversial. Anti-phospholipid antibodies are the hallmark of a syndrome that may comprise a number of neurological manifestations. Thus, anti-P and anti-phospholipid antibodies have both been associated with central nervous system involvement and their co-existence in the same sera was reported. We verified the ability of purified anti-P antibodies to bind different phospholipids and phospholipid-binding proteins in solid-phase assays. Anti-P antibodies from five of eight patients bound cardiolipin (CL) when saturated with fetal calf serum (FCS); in three cases anti-CL antibodies were also detected in the flow-through. No anti-P eluate, nor any corresponding flow-through, bound beta(2)-glycoprotein I alone or prothrombin. Moreover, no anti-P eluate bound CL when the plates were blocked with bovine serum albumin in the absence of FCS. Anti-P antibodies with anti-CL activity bound both ssDNA and dsDNA and also nucleosomes in three patients. Our data indicate a great heterogeneity of anti-P antibodies that appear to be overlapped partially with the other autoantibody populations detected frequently in SLE.
Department of Experimental Pathology, University of Pisa, Italy. l.caponi@med.unipi.it
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L
Caponi
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C
Anzilotti
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G
Longombardo
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Migliorini
D000918:Antibody Specificity; D001323:Autoantibodies / Q000378:metabolism*; D002308:Cardiolipins / Q000378:metabolism; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D010743:Phospholipids / Q000378:metabolism*; D011485:Protein Binding; D012269:Ribosomal Proteins / Q000276:immunology*
D001323:Autoantibodies; D002308:Cardiolipins; D010743:Phospholipids; D012269:Ribosomal Proteins