ABSTRACT

PatientswithEasilyDetectablelgGAutoantibodiesandlgMAutoantibodiesthatAreNot DefinedbyRoutineTests.IfroutineproceduresareusedtotesttheRBCsandserumofthis group,theresultswouldbethosemostcommonlyfoundinidiopathicWAIHA(e.g.,IgGor IgG+C3detectedontheRBCs;agglutinationandperhapslysisofenzyme-treatedRBCs;a positiveIATwithuntreatedandenzyme-treatedRBCs).Theseresultsareobtainedbecause anti-IgMisnotusedroutinelyfortheDATandIAT,andtheimmunoglobulinclassoftheserum antibody(ies)isnotusuallydetermined.Whenanti-IgMwasused,PetzandGarratty(3)found thatRBC-boundIgMwasdetectedon8%oftheRBCsofpatientswithwarmAIHA.Noneof the104patientshadonlyIgMontheRBCs;2%hadIgG+IgA+C3+IgM;4%hadIgG +IgM+C3;2%hadIgM+C3(seeTable3).Ifmoresensitivetestsareapplied,then RBC-boundIgMisdetectedmoreoften.Vosetal.(75)showedthat42%ofeluatesprepared fromtheRBCsof55patientswithWAIHAcontainedIgMand/orIgAinadditiontotheIgG detectedbytheDAT.UsingtheAutoAnalyzer,Hsuetal.(11)foundthat8of11(73%)patients withWAIHAassociatedwithIgGpositiveDATshadRBC-boundIgMpresentinaddition. Noneof16OAT-positivepatientswithoutAIHAhadRBC-boundIgM.UsingELAT,Sokol etal.(52)detectedIgMontheRBCsof39of102(38%)patientswithWAIHAassociated withIgG-positiveDATs.