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

Autoimmunity. 2011 Mar;44(2):90-7. doi: 10.3109/08916934.2010.499886. Epub 2010 Aug 9.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Antibodies, Antiphospholipid / blood
  • Antibodies, Antiphospholipid / immunology
  • Antibody Specificity
  • Antiphospholipid Syndrome / diagnosis
  • Antiphospholipid Syndrome / immunology*
  • Argonaute Proteins
  • Autoantibodies / blood*
  • Autoantibodies / 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

Substances

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