EnzymeimmunoassayforthequalitativeandquantitativedeterminationofIgGantibodiesagainstProteinase3(c-ANCA)(captureversion)inhumanserum.

Anti-neutrophilcytoplasmicantibodies(ANCA),originallyidentifiedbyimmunofluorescenceassays(IFA),aredirectedagainstcytoplasmiccomponentsofneutrophilgranulocytesandmonocytes.TheyhaveproventobeausefulSEROlogicMarkerforanumberofsystemic,autoimmunemediatedvasculitides.Agranularcytoplasmic(c-ANCA)stainingpatternoftheneutrophilsubstrateisindicativeforautoantibodiesagainstProteinase3(PR3),a29kDaserineproteinasepresentintheazurophilicgranulesofhumangranulocytesandmonocytes.PR3antibodiesoccurinpatientswithWegener"sgranulomatosis(WG),asystemicvasculitisaffectingtherespiratorytract.Theirspecificityisabout95%,theirsensitivitydependsonthephaseandactivityofthedisease.ThetiteroftheseantibodiesroughlyreflectsthecourseofWGandprovidesatooltocontrolthetherapyefficiency.ThepresentELISAisintendedforthequantitativeorqualitativedeterminationofIgGantibodiesinhumanserum,directedagainstPR3.ItiscalibratedagainsttheinternationalstandardforPR3-serology,AF-CDC(humanreferenceserum16,codeIS2721).TheimmobilisedantigenisahighlypurifiedpreparationofPR3,isolatedfromhumangranulocytes.Duringrecentyearsithasbeenshownthatcapturetechniqueofantigenimmobilisationachievesimprovedsensitivity,ascomparedtoconventional(adsorptive)fixation.ThepresentELISAtakesadvantagefromthistechnique,withtheadditionalfeaturethatthePR3moleculeisexposedintwodistinctlydifferentorientations.Thetestisfast(incubationtime30/30/30minutes)andflexIBLe(divisiblesolidphase,ready-to-usereagents).Sixcalibratorsallowquantitativemeasurements;anegativeandapositivecontrolchecktheassayperformance.