Medical Microbiology

ImmunologicalTestMethods......................................

AntigenandAntibodyAssays.............................

ImmunoprecipitationinLiquidsandGels............

Immunoprecipitate.Maximumprecipitationresultswhenbothreaction
partnersarepresentinanapproximatelyequivalentratio(Fig.2. 20 ).Inanti-
bodyexcess,orantigenexcess,theamountofprecipitateisconsiderablyre-
duced.

DoublediffusionaccordingtoOuchterlony.Thistechniqueallowsforaqua-
litativeevaluationofwhethercertainantibodiesorantigensarepresentor
not,plusdeterminationofthedegreeofrelationshipbetweenantibodies
andantigens.Italsoprovidesinformationonwhetherdifferentantigenicde-

ImmunologicalTestMethods 121

Immunoprecipitation

Fig.2. 20 Toidentifythe

unknownantigen,aknown

specificantibodyisadded

to an antigen mixture

whichisradio-,orother-

wise-,labeled.Theimmune

complexesareprecipitated

withthehelpofco-precipi-

tatingreagents(e.g.,anti-

immunoglobulin antibo-

dies). The precipitate is

thoroughlywashedtore-

move unbound antigen,

thendispersedintosolu-

tiononceagain(e.g.,in

SDS),afterwhichthecom-

ponents are separated

usingSDSpolyacrylamide

gel electrophoresis (SDS-

PAGE).Thelabeledantigen

isthenrenderedvisibleby

meansofautoradiography.

2

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Kayser, Medical Microbiology © 2005 Thieme

All rights reserved. Usage subject to terms and conditions of license.