TumorNecrosisFactor(TNF)wasoriginallydiscoveredinseraofanimalsandwasfoundtocausehemorrhagicnecrosisofsometransplantablemouseandhumantumorsandtoexhibitprimarilycytotoxicactivitiesagainsttumorbutnotnormalcellsinvitro.TheTNFfamilyconsistsoftwoproteinsdesignatedTNF-alpha,alsocalledcachectin,andTNF-beta,alsocalledlymphotoxin,whicharepleiotropiccytokinesthatcanmediateawidevarietyofBIOLOGicaleffects.
BothTNF-alphaandTNF-betahavebeenshowntointeractwithacellthroughspecifichighaffinityreceptorswithafewhundreduptomorethan20,000copiespercell.TNF-receptorshavebeendemonstratedonawidevarietyofhumansomaticcellsincludingfibroblasts,endothelialcells,ADIpocytes,livermembranes,granulocytesandseveraltumorcelllines.Normalandmalignanthumanmyeloidcellsaswellasmitogen-stimulatedlymphocytesexpresssimilarnumbersofTNFreceptors(400-1,900percell),whereasrestinglymphoidcellshavefewer,redbloodcellsandplateletshavenodetectableTNFreceptors.InmostcasesnocorrelationisobservedbetweenreceptornumberandsensitivitytoTNF.Basedongelfiltrationexperimentsthereceptorappearstobeacomplexofdifferentproteinswithamolecularweightof350kDa.InavarietyofcelllinestwodifferenttypesofTNFreceptorswith75-80and55-60kDarespectivelyhavebeenidentified(7,11,23).Thepresentassay,slightlymodifiedfromtheassayestablishedbyAdolfandApfler,providesasimple,rapid,andhighlysensitivemethodforthedeterminationofsolubleTNF-R(60kDa)levelsinbodyfluidsorcellculturesupernatants.ThisassaywillhelptoclarifythepossIBLediagnosticandprognosticvalueofcirculatingsTNF-R(60kDa)invariousneoplasticandinflammatorydiseases.

Synonyms:TNFreceptorsuperfamilymember1A;p60;p55;CD120aantigen