EnzymeimmunoassayforthequalitativedeterminationofIgMclassantibodiesagainstAspergillusfumigatusinhumanserumorplasma(citrate,heparin).AspergillusfumigatusisafungusofthegenusAspergillus,andisoneofthemostcommonAspergillusspeciestocausediseaseinindividualswithanimmunodeficiency.A.fumigatus,asaprotrophwidespreadinnature,istypicallyfoundinsoilanddecayingorganicmatter.Coloniesofthefungusproducethousandsofsmallconidia(2-3μm)thatreADIlybecomeairborne.Thefungusiscapableofgrowthattemperaturesupto50°C,withconidiasurvivingat70°C.Humansarecontinuouslyincontactwiththeseasexualsporesanditisestimatedthatanindividualinhalesseveralhundredconidiaeachday;typicallythesearequicklyeliminatedbytheimmunesystem.Aspergillosisdevelopsmainlyinindividualswhoareimmunocompromised,eitherfromdiseaseorfromimmunosuppressivedrugs,andisaleadingcauseofdeathinacuteleukemiaandhematopoieticstemcelltransplantation.ThetermaspergillosiscomprisesanumberofdifferentdiseasescausedbyfungiofthegenusAspergillus.Themostcommonformsareallergicbronchopulmonaryaspergillosis(ABPA),pulmonaryaspergillomaandinvasiveaspergillosis(IA).AllergicbronchopulmonaryaspergillosisischaracterizedbyanexaggeratedresponseoftheimmunesystemtoAspergillusspecies.Itoccursinpatientssufferingfromasthmaorcysticfibrosis.Clinically,ABPAmanifestsasabronchialasthmawithtransientpulmonaryinfiltratesthatmayproceedtoproximalbronchiectasisandlungfibrosis.Aspergilloma,commonlyreferredtoas“fungusball,”occursinpreexistingpulmonarycavitiesthatwerecausedbytuberculosis,sarcoidosis,orotherbullouslungdisorders.Thefungussettlesinacavityandgrowsuntilitformsacompactsphere,whichincorporatesdeadtissuefromthesurroundinglung,mucus,andotherdebris.Patientsareusuallyasymptomaticandoftenco-existfordecadeswithaspergillomaepriortoincidentaldiagnosis.However,itmaycausehemoptysis.Invasiveaspergillosisisarapidlyprogressive,oftenfataldisease,targetingseverelyimmunocompromisedpatients,includingthosewithhematologicalmalignanciessuchasleukemia,thosewhohavereceivedsolidorganorhematopoieticstemcelltransplants,andindividualswithchronicgranulomatousdiseaseoradvancedAIDS.IAischaracterizedbyinvasionofbloodvessels,resultinginmultifocalinfiltrates.Disseminationtootherorgans,particularlythecentralnervoussystem,mayoccur.ThequalitativeimmunoenzymaticdeterminationofIgM-classantibodiesagainstAspergillusfumigatusisbasedontheELISA(Enzyme-linkedImmunosorbentAssay)technique.MicrotiterstripwellsarecoatedwithAspergillusfumigatusantigenstobindcorrespondingantibodiesofthespecimen.Afterwashingthewellstoremoveallunboundsamplematerialhorseradishperoxidase(HRP)labelledanti-humanIgMconjugateisadded.ThisconjugatebindstothecapturedAspergillusfumigatusspecificantibodies.TheimmunecomplexformedbytheboundconjugateisvisualizedbyaddingTetramethylbenzidine(TMB)substratewhichgivesabluereactionproduct.TheintensityofthisproductisproportionaltotheamountofAspergillusfumigatus-specificIgMantibodiesinthespecimen.Sulphuricacidisaddedtostopthereaction.Thisproducesayellowendpointcolour.Absorbanceat450nmisreadusinganELISAmicrowellplatereader.ThequalitativeimmunoenzymaticdeterminationofIgM-classantibodiestoAspergillusfumigatusisbasedontheELISA(Enzyme-linkedImmunosorbentAssay)technique.