BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCA) with a C-ANCA or P-ANCA pattern are detected in ANCA-associated vasculitis (AAV). While in most patients with AAV a C-ANCA pattern is due to reactivity with proteinase-3 (PR3)-ANCA, some C-ANCA-positive sera do not react with PR3. OBJECTIVE: The development and evaluation of a direct enzyme-linked immunosorbent assay (ELISA) for PR3-ANCA with increased sensitivity. METHODS: A mixture of human native (hn) and human recombinant (hr) PR3 was used as antigen coating. The resulting ELISA (anti-PR3-hn-hr) was compared with ELISAs using directly coated hn-PR3 or hr-PR3, as well as with a hn-PR3 capture ELISA. Assay characteristics were determined in patients with AAV (n = 248), with special attention for those patients with C-ANCA (n = 132), as well as disease controls (n = 585) and healthy controls (n = 429). Additionally, for prediction of relapses serial samples of 46 patients with PR3-AAV were analysed. RESULTS: At a predefined specificity of 99% both ELISAs containing hr-PR3 revealed a substantial increase in sensitivity. For the prediction of relapses by rises in PR3-ANCA titres the capture ELISA was most optimal (odds ratio 12.5). With an odds ratio of 8.9 the novel anti-PR3-hn-hr ELISA was second best. CONCLUSIONS: Owing to the very high sensitivity of the novel anti-PR3-hn-hr ELISA for the detection of PR3-ANCA in C-ANCA-positive samples of patients with AAV this assay has an excellent diagnostic performance. This feature is combined with a good predictability of clinical relapses in patients with PR3-AAV. These characteristics challenge the dogma that, for detection of PR3-ANCA, capture ELISAs are superior for diagnosis and follow-up.
BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCA) with a C-ANCA or P-ANCA pattern are detected in ANCA-associated vasculitis (AAV). While in most patients with AAV a C-ANCA pattern is due to reactivity with proteinase-3 (PR3)-ANCA, some C-ANCA-positive sera do not react with PR3. OBJECTIVE: The development and evaluation of a direct enzyme-linked immunosorbent assay (ELISA) for PR3-ANCA with increased sensitivity. METHODS: A mixture of human native (hn) and human recombinant (hr) PR3 was used as antigen coating. The resulting ELISA (anti-PR3-hn-hr) was compared with ELISAs using directly coated hn-PR3 or hr-PR3, as well as with a hn-PR3 capture ELISA. Assay characteristics were determined in patients with AAV (n = 248), with special attention for those patients with C-ANCA (n = 132), as well as disease controls (n = 585) and healthy controls (n = 429). Additionally, for prediction of relapses serial samples of 46 patients with PR3-AAV were analysed. RESULTS: At a predefined specificity of 99% both ELISAs containing hr-PR3 revealed a substantial increase in sensitivity. For the prediction of relapses by rises in PR3-ANCA titres the capture ELISA was most optimal (odds ratio 12.5). With an odds ratio of 8.9 the novel anti-PR3-hn-hr ELISA was second best. CONCLUSIONS: Owing to the very high sensitivity of the novel anti-PR3-hn-hr ELISA for the detection of PR3-ANCA in C-ANCA-positive samples of patients with AAV this assay has an excellent diagnostic performance. This feature is combined with a good predictability of clinical relapses in patients with PR3-AAV. These characteristics challenge the dogma that, for detection of PR3-ANCA, capture ELISAs are superior for diagnosis and follow-up.
Authors: Gunnar Tomasson; Peter C Grayson; Alfred D Mahr; Michael Lavalley; Peter A Merkel Journal: Rheumatology (Oxford) Date: 2011-10-29 Impact factor: 7.580
Authors: E M Miloslavsky; U Specks; P A Merkel; P Seo; R Spiera; C A Langford; G S Hoffman; C G M Kallenberg; E W St Clair; N K Tchao; L Viviano; L Ding; D Iklé; M Villarreal; B Jepson; P Brunetta; N B Allen; F C Fervenza; D Geetha; K Keogh; E Y Kissin; P A Monach; T Peikert; C Stegeman; S R Ytterberg; J H Stone Journal: Arthritis Rheumatol Date: 2014-11 Impact factor: 10.995
Authors: Ulrich Specks; Peter A Merkel; Philip Seo; Robert Spiera; Carol A Langford; Gary S Hoffman; Cees G M Kallenberg; E William St Clair; Barri J Fessler; Linna Ding; Lisa Viviano; Nadia K Tchao; Deborah J Phippard; Adam L Asare; Noha Lim; David Ikle; Brett Jepson; Paul Brunetta; Nancy B Allen; Fernando C Fervenza; Duvuru Geetha; Karina Keogh; Eugene Y Kissin; Paul A Monach; Tobias Peikert; Coen Stegeman; Steven R Ytterberg; Mark Mueller; Lourdes P Sejismundo; Kathleen Mieras; John H Stone Journal: N Engl J Med Date: 2013-08-01 Impact factor: 91.245