Description:
TheREAADSAnti-Phosphatidylserine(aPS)IgG/IgMtestkitisaindirect,semi-quantitativeELISAusedtodetectantibodiesagainstphosphatidylserine.EachassayusesasingleormultipointcalibratortoobtainIgG/IgManti-phosphatidylserineantibodicconcentrationsfrompatientsamples.
Advantages:
- ConvenientELISAProcedure
- ForthespecificdeterminationofIgG/IgMisotypes
- Objective,accurateandreproducIBLe
- Reagentcompletekits
- Totalincubationtime:40minutesatroomtemperature
- EasilyAutomated
- Choiceofsingleormulti-pointcalibration
PrincipleandProcedure:
Principle
TheREAADSIgG,IgMandIgAAnti-Phosphatidylserine(aPS)TestKitsareindirect,semi-quantitativeELISAsusedtodetectantibodiesagainstphosphatidylserine.EachassayusesasingleormultipointcalibratortoobtainIgG,IgMorIgAanti-phosphatidylserineantibodyconcentrationsfrompatientsamples.
Procedure
Patientserumisdilutedintosamplediluentcontainingbovineserum(sourceofcofactor)andincubatedinwellscoatedwithphosphatidylserine.AnyaPSantibodiespresentinthepatientsamplewillbindtothecoatedwells.Afterremovalofunboundserumbywashing,antibodiesspecificforhumanIgG,IgMorIgAlabeledwithhorserADIshperoxidase(HRP),areaddedtoformcomplexeswiththephosphatidylserineboundantibodies.
Thewellsarewashed,andachromogenicsubstrateisadded,resultinginacolorchangethatisproportionaltotheamountofantibodypresent.Theassayisstoppedbytheadditionofastoppingsolution.ResultsareobtainedbyreadingtheO.D.(opticaldensity)ofeachwellat450nminaspectrophotometer.TheO.D.valuesofcontrolandpatientsamplesaremultipliedbythecalibratorconversionfactortoobtainIgG,IgMorIgAanti-phosphatidylserineantibodyconcentrationsinGPS,MPSorAPSunits,respectively.Assaycutoffshavebeenestablishedat16GPS,22MPSand20APSunits.
ClinicalPerformance:
ClinicalSpecificity
Serumsamplesfrommultiplehealthyblooddonorpopulationswereassayedforthepresenceofantiphosphatidylserineantibodies.Specificitywasshowntobe96%forbothIgGandIgMantibodies,and95%forIgA.
ClinicalSensitivity
UnselectedSLEsamplesweretestedtodeterminetheclinicalsensitivityoftheaPSassay.Theresultingsensitivitywas22.2%forIgG,25%forIgMand11.1%forIgA.TheclinicalsensitivityoftheassayforAntiphospholipidSyndrome(APS)wasdeterminedbycomparingaPStestresultsfromtwogroupsofselectedpatients:
| Group1–PrimaryAPS | IgGaPS | IgMaPS | IgAaPS |
| Assaycutoff | 16GPS | 22MPS | 20APS |
| Averagevalue | 61.6GPS | 33.4MPS | 21.1APS |
| %positive | 90.9% | 54.5% | 36.4% |
| Group2–SLEcontrol | IgGaPS | IgMaPS | IgAaPS |
| Assaycutoff | 16GPS | 22MPS | 20APS |
| Averagevalue | 9.2GPS | 9.9MPS | 11.2APS |
| %positive | 11.1% | 11.1% | 0% |
- Group1–patientswithPrimaryAPS
- Group2–SLEpatientswithnohistoryofthrombosisorthrombocytopenia(controls).Theresultsareshowninthechartabove.
TheprevalenceandmeanlevelsofaPSantibodieswerehigherinPrimaryAPSpatientsthanintheSLEcontrolgroup.Theseassays,whenruninconcertwithadditionalanti-phospholipidandlupusanticoagulantassays,providesamorecompleteprofileforestablishingadiagnosisofAntiphospholipidSyndromeandforassessingtheriskofthromboticcomplicationsinSLEpatients.
Background:
Elevatedserumlevelsofanti-phospholipidantibodiesareassociatedwithanincreasedriskforrecurrentarterialandvenousthromboticevents,thrombocytopeniaandfetalloss.ThesearethemainclinicalmanifestationsofAntiphospholipid
Syndrome.Phosphatidylserineisfoundinthemembranesofplateletsandendothelialcells,whichparticipateinthecoagulationcascade.Duetoitsphysiologicrole,testingforautoantibodiesdirectedtowardsphosphatidylserineprovidesnotonlymorerelevantresults,butalsoadditionalinformationtoassesstheriskofthrombosis.
