▁basic ▁T ▁cell ▁research . ▁ ▁Classic ▁methods ▁in ▁T ▁cell ▁research ▁T ▁cells ▁play ▁an ▁important ▁role ▁in ▁the ▁adapt ive ▁imm une ▁system . ▁They ▁are ▁capable ▁of ▁orch estr ating , ▁reg ulating ▁and ▁coordin ating ▁complex ▁imm une ▁responses . ▁A ▁wide ▁array ▁of ▁clin ically ▁relevant ▁aspects ▁are ▁associated ▁with ▁the ▁function ▁or ▁mal function ▁of ▁T - cell s : ▁Auto imm une ▁dise ases , ▁control ▁of ▁vir al ▁or ▁b acter ial ▁path og ens , ▁development ▁of ▁cancer ▁or ▁gra ft ▁versus ▁host ▁responses . ▁Over ▁the ▁past ▁years , ▁various ▁methods ▁( EL IS pot ▁Ass ay , ▁int rac ell ular ▁cy tok ine ▁st aining , ▁secret ion ▁ass ay ) ▁have ▁been ▁developed ▁for ▁the ▁identification ▁of ▁T ▁cells , ▁but ▁only ▁major ▁h isto compat ibility ▁complex ▁( M HC ) ▁procedures ▁allow ▁identification ▁and ▁pur ification ▁of ▁ant igen - specific ▁T ▁cells ▁independent ▁of ▁their ▁functional ▁status . ▁ ▁In ▁principle , ▁M HC ▁procedures ▁are ▁using ▁the ▁T ▁cell ▁re ceptor ▁( TC R ) ▁lig and , ▁which ▁is ▁the ▁M HC - pe pt ide ▁complex , ▁as ▁a ▁st aining ▁pro be . ▁The ▁M HC ▁interact s ▁with ▁the ▁T CR , ▁which ▁in ▁turn ▁is ▁expressed ▁on ▁the ▁T ▁cells . ▁Because ▁T CR - M HC ▁interactions ▁have ▁only ▁a ▁very ▁weak ▁aff inity ▁towards ▁each ▁other , ▁mon omer ic ▁M HC - ep ito pe ▁complex es ▁cannot