Medical Microbiology

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.