0 10 Occurrence occurrence NN 11 13 of of IN 14 15 a a DT 16 24 silencer silencer NN 25 27 of of IN 28 31 the the DT 32 45 interleukin-2 interleukin-2 NN 46 50 gene gene NN 51 53 in in IN 54 59 naive naive JJ 60 63 but but CC 64 67 not not RB 68 70 in in IN 71 77 memory memory NN 78 85 resting rest VBG 86 87 T t NN 88 94 helper helper NN 95 106 lymphocytes lymphocyte NNS 106 107 . . . 109 111 In in IN 112 115 the the DT 116 122 immune immune JJ 123 129 system system NN 130 133 the the DT 134 139 first first JJ 140 150 activation activation NN 151 153 of of IN 154 155 a a DT 156 161 naive naive JJ 162 163 T t NN 164 168 cell cell NN 169 171 by by IN 172 179 antigen antigen NN 180 182 is be VBZ 183 184 a a DT 185 188 key key JJ 189 193 step step NN 194 196 in in IN 197 200 the the DT 201 208 shaping shaping NN 209 211 of of IN 212 215 the the DT 216 226 peripheral peripheral JJ 227 228 T t NN 229 233 cell cell NN 234 245 specificity specificity NN 246 256 repertoire repertoire NN 257 260 and and CC 261 272 maintenance maintenance NN 273 275 of of IN 276 290 self-tolerance self-tolerance NN 290 291 . . . 292 294 In in IN 295 298 the the DT 299 306 present present JJ 307 312 study study NN 312 313 , , , 314 322 analysis analysis NN 323 325 of of IN 326 329 the the DT 330 343 interleukin-2 interleukin-2 NN 344 345 ( ( ( 345 349 IL-2 il-2 NN 349 350 ) ) ) 351 355 gene gene NN 356 366 activation activation NN 367 372 shows show VBZ 373 377 that that IN 378 383 naive naive JJ 384 389 human human JJ 390 396 helper helper NN 397 398 T t NN 399 404 cells cell NNS 405 406 ( ( ( 406 410 cord cord NN 411 416 blood blood NN 417 421 CD4+ cd4+ JJ 422 423 T t NN 424 429 cells cell NNS 429 430 , , , 431 436 adult adult JJ 437 448 CD4+CD45RO- cd4+cd45ro- JJ 449 450 T t NN 451 456 cells cell NNS 456 457 ) ) ) 458 466 regulate regulate VBP 467 471 IL-2 il-2 NN 472 485 transcription transcription NN 486 488 by by IN 489 490 a a DT 491 500 mechanism mechanism NN 501 510 involving involve VBG 511 515 both both CC 516 517 a a DT 518 526 silencer silencer NN 527 530 and and CC 531 533 an an DT 534 543 activator activator NN 544 550 acting act VBG 551 553 on on IN 554 557 the the DT 558 569 purine-rich purine-rich JJ 570 574 IL-2 il-2 NN 575 583 promoter promoter NN 584 592 elements element NNS 593 594 ( ( ( 594 599 NF-AT NF-AT NNP 600 607 binding binding NN 608 613 sites site NNS 613 614 ) ) ) 614 615 . . . 616 618 By by IN 619 627 contrast contrast NN 627 628 , , , 629 635 memory memory NN 636 641 cells cell NNS 641 642 , , , 643 649 either either CC 650 652 in in FW 653 658 vitro vitro FW 659 668 activated activate VBN 669 675 helper helper NN 676 677 T t NN 678 683 cells cell NNS 684 693 reverting revert VBG 694 696 to to TO 697 698 a a DT 699 706 resting resting JJ 707 712 state state NN 712 713 , , , 714 716 or or CC 717 721 CD4+ cd4+ JJ 722 723 T t NN 724 725 ( ( ( 725 731 memory memory NN 731 732 ) ) ) 733 739 clones clone NNS 739 740 , , , 741 743 or or CC 744 755 CD4+CD45RO+ cd4+cd45ro+ JJ 756 757 T t NN 758 763 cells cell NNS 764 772 isolated isolate VBN 773 775 ex ex FW 776 780 vivo vivo FW 780 781 , , , 782 784 no no RB 785 791 longer longer RB 792 796 have have VB 797 798 a a DT 799 807 silencer silencer NN 807 808 . . . 809 814 Their their PRP$ 815 819 IL-2 il-2 NN 820 833 transcription transcription NN 834 839 seems seem VBZ 840 842 to to TO 843 845 be be VB 846 856 controlled control VBN 857 863 solely solely RB 864 866 by by IN 867 870 the the DT 871 881 transition transition NN 882 886 from from IN 887 895 inactive inactive JJ 896 898 to to TO 899 905 active active JJ 906 916 functional functional JJ 917 922 state state NN 923 925 of of IN 926 927 a a DT 928 936 positive positive JJ 937 950 transcription transcription NN 951 957 factor factor NN 958 965 binding bind VBG 966 968 to to TO 969 974 these these DT 975 983 promoter promoter NN 984 992 elements element NNS 993 995 as as RB 996 1000 well well RB 1001 1003 as as IN 1004 1007 its its PRP$ 1008 1019 cytoplasmic cytoplasmic JJ 1020 1022 or or CC 1023 1030 nuclear nuclear JJ 1031 1039 location location NN 1039 1040 : : : 1041 1043 in in IN 1044 1051 resting rest VBG 1052 1058 memory memory NN 1059 1060 T t NN 1061 1066 cells cell NNS 1067 1070 the the DT 1071 1080 activator activator NN 1081 1083 is be VBZ 1084 1091 located locate VBN 1092 1094 in in IN 1095 1098 the the DT 1099 1108 cytoplasm cytoplasm NN 1109 1112 and and CC 1113 1115 is be VBZ 1116 1124 inactive inactive JJ 1124 1125 , , , 1126 1133 whereas whereas IN 1134 1136 in in IN 1137 1147 stimulated stimulate VBN 1148 1153 cells cell NNS 1154 1156 it it PRP 1157 1159 is be VBZ 1160 1170 functional functional JJ 1171 1173 in in IN 1174 1183 promoting promote VBG 1184 1197 transcription transcription NN 1198 1201 and and CC 1202 1205 now now RB 1206 1213 resides reside VBZ 1214 1216 in in IN 1217 1220 the the DT 1221 1228 nucleus nucleus NN 1228 1229 . . . 1230 1234 Thus thus RB 1234 1235 , , , 1236 1239 the the DT 1240 1250 regulation regulation NN 1251 1253 of of IN 1254 1257 the the DT 1258 1262 gene gene NN 1263 1269 coding cod VBG 1270 1273 for for IN 1274 1277 the the DT 1278 1282 main main JJ 1283 1284 T t NN 1285 1289 cell cell NN 1290 1296 growth growth NN 1297 1303 factor factor NN 1304 1311 changes change NNS 1312 1324 irreversibly irreversibly RB 1325 1330 after after IN 1331 1334 the the DT 1335 1340 first first JJ 1341 1350 encounter encounter NN 1351 1353 of of IN 1354 1355 T t NN 1356 1361 cells cell NNS 1362 1366 with with IN 1367 1374 antigen antigen NN 1374 1375 . . . 1376 1378 It it PRP 1379 1381 is be VBZ 1382 1386 most most RBS 1387 1393 likely likely JJ 1394 1398 that that IN 1399 1402 the the DT 1403 1411 presence presence NN 1412 1414 of of IN 1415 1416 a a DT 1417 1425 silencer silencer NN 1426 1437 contributes contribute VBZ 1438 1440 to to TO 1441 1444 the the DT 1445 1449 more more RBR 1450 1459 stringent stringent JJ 1460 1470 activation activation NN 1471 1483 requirements requirement NNS 1484 1486 of of IN 1487 1492 naive naive JJ 1493 1497 CD4+ cd4+ JJ 1498 1499 T t NN 1500 1505 cells cell NNS 1505 1506 . . .