precipitatecanthenbestainedandevaluated.Thisoldermethodisstillused
toidentifyparaproteins,monoclonalimmunoglobulins,etc.(Fig.2. 23 ).
Electrophoresisplusantibodyreaction:Westernblotting.Thismethodin-
volveselectrophoresisofproteinsinagel,coupledwithdetectionbyspecific
antibodies.Theseparatedproteinsaretransferredtonitrocellulose,where
theyareidentifiedwiththehelpofspecificantibodies(Fig.2. 24 ).Polyclonal
seraisnormallyusedforthispurposeasmonoclonalantibodiesonlyrarely
bindtodenaturatedandseparatedproteins.
AgglutinationReaction
Antibodiescanagglutinateantigen-loadedparticles(Fig.2. 25 ),whilstanti-
genscanagglutinateantibody-loadedparticles.Application:agglutination
ofbacteriaorerythrocytes(e.g.,bloodgrouptests).
ImmunologicalTestMethods 123
RadialImmunodiffusionAccordingtoMancini
(Ring diame
ter)
2
Antigen concentration
0 10 25 50 100
Standard curve
Ag Ag Ag Ag
Gel containing Ab
Precipitin ring
Fig.2. 22 Quantitativeassayofanantigenusingamonospecificanti-serumwhich
ismixedwithagarandpouredintoaplate.Theantigenisthendilutedtodifferent
concentrations,andpipettedintowellsthathavebeenpreviouslypunchedintothe
plate.Antigen-antibodycomplexesprecipitateintheformofaringaroundthe
well,thediameterofwhichisproportionaltotheantigenconcentration.Theresult
isastandardcurvefromwhichunknowntestantigenscanbequantified.Analo-
gously,antibodiescanalsobequantifiedbymixingantigensintothegel.
2
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Kayser, Medical Microbiology © 2005 Thieme
All rights reserved. Usage subject to terms and conditions of license.