Simultaneous automated screening and confirmatory testing for vasculitis-specific ANCA

PLoS One. 2014 Sep 16;9(9):e107743. doi: 10.1371/journal.pone.0107743. eCollection 2014.

Abstract

Anti-neutrophil cytoplasmic antibodies (ANCA) are the serological hallmark of small vessel vasculitis, so called ANCA-associated vasculitis. The international consensus requires testing by indirect immunofluorescence (IIF) on human ethanol-fixed neutrophils (ethN) as screening followed by confirmation with enzyme-linked immunosorbent assays (ELISAs). This study evaluates the combination of cell- and microbead-based digital IIF analysis of ANCA in one reaction environment by the novel multiplexing CytoBead technology for simultaneous screening and confirmatory ANCA testing. Sera of 592 individuals including 118 patients with ANCA-associated vasculitis, 133 with rheumatoid arthritis, 49 with infectious diseases, 77 with inflammatory bowel syndrome, 20 with autoimmune liver diseases, 70 with primary sclerosing cholangitis and 125 blood donors were tested for cytoplasmic ANCA (C-ANCA) and perinuclear ANCA (P-ANCA) by classical IIF and ANCA to proteinase 3 (PR3) and myeloperoxidase (MPO) by ELISA. These findings were compared to respective ANCA results determined by automated multiplex CytoBead technology using ethN and antigen-coated microbeads for microbead immunoassays. There was a good agreement for PR3- and MPO-ANCA and a very good one for P-ANCA and C-ANCA by classical and multiplex analysis (Cohen's kappa [κ] = 0.775, 0.720, 0.876, 0.820, respectively). The differences between classical testing and CytoBead analysis were not significant for PR3-ANCA, P-ANCA, and C-ANCA (p<0.05, respectively). The prevalence of confirmed positive ANCA findings by classical testing (IIF and ELISA) compared with multiplex CytoBead analysis (IIF and microbead immunoassay positive) resulted in a very good agreement (κ = 0.831) with no significant difference of both methods (p = 0.735). Automated endpoint-ANCA titer detection in one dilution demonstrated a very good agreement with classical analysis requiring dilution of samples (κ = 0.985). Multiplexing by CytoBead technology can be employed for simultaneous screening and quantitative confirmation of ANCA. This novel technique provides fast and cost-effective ANCA analysis by automated digital IIF for the first time.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Antineutrophil Cytoplasmic / immunology*
  • Child
  • Enzyme-Linked Immunosorbent Assay / methods
  • Enzyme-Linked Immunosorbent Assay / standards
  • Female
  • Fluorescent Antibody Technique, Indirect / methods
  • Fluorescent Antibody Technique, Indirect / standards
  • Humans
  • Male
  • Middle Aged
  • ROC Curve
  • Reference Values
  • Reproducibility of Results
  • Vasculitis / diagnosis*
  • Vasculitis / immunology*
  • Young Adult

Substances

  • Antibodies, Antineutrophil Cytoplasmic

Grants and funding

This work was supported by the Federal Ministry of Economics and Technology Central Innovation Programme SME ZIM-KOOP (grants KF2379003AJ0, KF2379004AJ1) and the Federal Ministry of Education (Research projects InnoProfile 03IP611, InnoProfile-Transfer 03IPT611A and InnoProfile-Transfer 03IP611X). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.