ssDNAIgMELISAisasolidphaseenzymeimmunoassaywithhumanrecombinantsingle-strandedDNA(ssDNA)forthequantitativedetectionofIgMantibodiesagainstssDNAinhumanserum.AntibodiesagainstssDNAmainlyrecognizeitsbasiccompound,whichismaskedinsidethehelicalstructureofnativeDNA.Theassayisatoolinthedifferentialdiagnosisofsystemiclupuserythematosus(SLE).AntibodiesbindingtoDNAbelongtothegroupofanti-nuclearantibodies(ANA)whichoccurinseveralautoimmunediseases.Antibodiesreactingwithnativedouble-stranded(ds)DNAareregardedasbeingspecificforsystemiclupuserythematosus(SLE)andappearinapproximately50-80%ofthesepatients.AntibodiesagainstdsDNAarefoundduringactivephasesofSLE,theirserumconcentrationcorrelateswiththeseverityofthedisease.Thus,detectionoftheseautoantibodiesisimportantforthediagnosisandclinicalmonitoringofthediseaseandconsequentlyhasbeenestablishedas1ofthe11ACR-criteriaforthediagnosisofSLE.Antibodiestosingle-stranded(ss)DNAarefoundwithafrequencyofupto87%duringacutephasesand43%duringinactivephasesinpatientswithSLE.TheyarenotspecificforSLEastheymaybefoundinotherdiseaseslikeinfectiousmononucleosis(40%),autoimmunehepatitis(58%),acutemyeloidleukemia(89%),acutelymphaticleukemia,chronicmyeloidleukemia(60%)andjuvenilerheumatoidarthritis(35-50%),too.SLE-likesymptomsmaybeinducedbydrugs,too.Asanti-ssDNAantibodiesarefoundwithafrequencyofupto50%inpatientswithadrug-inducedLE,thedeterminationofantibodiesagainstssDNAisveryhelpfulforthedifferentialdiagnosis