Anti-argonaute2 (Ago2/Su) and -Ro antibodies identified by immunoprecipitation in primary anti-phospholipid syndrome (PAPS).

Abstract

OBJECTIVES:

Primary anti-phospholipid syndrome (PAPS) is an autoimmune condition defined by anti-phospholipid antibodies (aPL) and thrombotic or obstetric events. Some PAPS can evolve into systemic lupus erythematosus (SLE) during follow-up. Few studies systematically examined lupus autoantibodies and their clinical significance in PAPS. The aim of our study is to analyze the clinical and laboratory correlations with lupus-related autoantibodies, detected by immunoprecipitation (IP), a technique not yet systematically applied to investigate autoantibodies in this condition.

METHODS:

Sera from 52 PAPS patients were screened by indirect immunofluorescence (IIF) antinuclear antibodies (ANA), IP of ³⁵S-labeled K562 cell extract, and ELISA [anti-Argonaute2 (Ago2, Su), 60kRo, 52kRo, La, dsDNA)]. Anti-Ago2/Su positive sera were also tested for anti-GW bodies (GWBs) by IIF double staining, using rabbit anti-Rck/p54 serum.

RESULTS:

First, 56% of PAPS patients (29/52) were ANA positive, mainly with speckled pattern. Anti-Ago2/Su antibodies were found in 13% (7/52), anti-Ro/SSA in 10% (5/52), anti-La in one case. The clinical profile of patients did not seem to be related to the presence of these antibody specificities. However, levels of IgG anti-β2 glycoprotein I antibodies were lower in anti-Ago2/Su positive patients (p = 0.02). None of anti-Ago2/Su or -Ro patients developed SLE during a 2-year follow-up. Ago2 is a key component of GWBs, however, only 1/7 anti-Ago2/Su serum showed a typical cytoplasmic GWBs staining.

CONCLUSIONS:

Anti-Ago2/Su and -Ro antibodies are the two autoantibodies detected by IP in our PAPS cohort. Clarifying why Ago2/Su and Ro are specific targets of autoimmunity may help to understand the mechanisms of autoantibody production.

• Authors: Angela Ceribelli, Angela Tincani, Ilaria Cavazzana, Franco Franceschini, Roberto Cattaneo, Brad A Pauley, Jason Y F Chan, Edward K L Chan, Minoru Satoh
• Journal: Autoimmunity (Autoimmunity) Vol. 44 Issue 2 Pg. 90-7 (Mar 2011) ISSN: 1607-842X [Electronic] England
• PMID: 20695766 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• AGO2 protein, human
• Antibodies, Antiphospholipid
• Argonaute Proteins
• Autoantibodies
• Eukaryotic Initiation Factor-2
• Ribonucleoproteins
• SS-A antigen

Topics

• Adult
• Animals
• Antibodies, Antiphospholipid (blood, immunology)
• Antibody Specificity
• Antiphospholipid Syndrome (diagnosis, immunology)
• Argonaute Proteins
• Autoantibodies (blood, immunology)
• Dogs
• Enzyme-Linked Immunosorbent Assay
• Eukaryotic Initiation Factor-2 (immunology)
• Female
• Humans
• Immunoprecipitation (methods)
• Lupus Erythematosus, Systemic (immunology)
• Male
• Mice
• Middle Aged
• Rabbits
• Ribonucleoproteins (immunology)
• Young Adult