segment_22 - Gener at ion of t he M H C Class I I /Pept ide...

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Unformatted text preview: Gener at ion of t he M H C Class I I /Pept ide Complex P r ocessing of Exogenous Ag • Enzymes have acidic optima. • Pr ocessing can be inhibited by chemicals t hat incr ease pH , such as chlor oquine. • Peptides gener ated ar e 13-18 amino acids l ong. T he TCR int er act s wit h bot h t he pept ide and t he M H C m olecules. T he cellular dist r ibut ion of M H C Class I and M H C Class I I molecules differ s. M H C Class I is on all nucleat ed cells. M H C Class I I is pr edominant ly f ound on pr ofessional ant igen-pr esent ing cells. R egulation of M H C • Some cytok ines (I nter fer ons α , β , γ a nd T N F ) u pr egulate M H C class I H eightened antivir al immunity. • I nter fer on-γ i ncr eases M H C class I I expr ession H ( except in B cells). T p r oduce I F N -γ t o activate m acr ophages. • M any vir uses r educe M H C expr ession, par ticular ly class I : A denovir us 12, H epatitis B, Cytomegalovir us. O f cour se, this is counter ed by N K cell r ecognition of r educed class I . • M H C and I mmune R esponsiveness M H C haplotype is the major deter minant of d iffer ences in i mmune r esponsiveness betw een i ndividuals. • T w o mechanisms• D eter minant-Selection: D iffer ent M H C molecules differ in a bility to bind pr ocessed Ag. • H oles-in-the-Reper toir e: T cell w ith r eceptor that binds f or eign Ag pepti de/M H C is elimi nated dur ing matur ation if t her e is a self-Ag peptide/M H C r esembling the for eign Ag p eptide/M H C. ...
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This note was uploaded on 04/27/2010 for the course MMG 451 taught by Professor Brooks during the Spring '08 term at Michigan State University.

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segment_22 - Gener at ion of t he M H C Class I I /Pept ide...

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