0 9 Molecular molecular JJ 10 20 regulation regulation NN 21 23 of of IN 24 32 cytokine cytokine NN 33 37 gene gene NN 38 48 expression expression NN 49 55 during during IN 56 59 the the DT 60 66 immune immune JJ 67 75 response response NN 75 76 . . . 78 86 Cytokine Cytokine NNP 87 97 expression expression NN 98 100 by by IN 101 107 immune immune JJ 108 114 system system NN 115 120 cells cell NNS 121 126 plays play VBZ 127 129 an an DT 130 139 important important JJ 140 144 role role NN 145 147 in in IN 148 151 the the DT 152 162 regulation regulation NN 163 165 of of IN 166 169 the the DT 170 176 immune immune JJ 177 185 response response NN 185 186 . . . 187 189 On on IN 190 195 first first JJ 196 205 encounter encounter NN 206 210 with with IN 211 218 antigen antigen NN 218 219 , , , 220 225 naive naive JJ 226 230 CD4+ cd4+ JJ 231 232 T t NN 233 239 helper helper NN 240 241 ( ( ( 241 243 Th Th NNP 243 244 ) ) ) 245 250 cells cell NNS 251 264 differentiate differentiate VBP 265 269 into into IN 270 288 cytokine-producing cytokine-producing JJ 289 297 effector effector NN 298 303 cells cell NNS 303 304 . . . 305 308 Two two CD 309 314 types type NNS 315 317 of of IN 318 326 effector effector NN 327 332 cells cell NNS 333 346 characterized characterize VBN 347 349 by by IN 350 355 their their PRP$ 356 364 distinct distinct JJ 365 375 expression expression NN 376 378 of of IN 379 387 cytokine cytokine NN 388 396 profiles profile NNS 397 401 have have VBP 402 406 been be VBN 407 416 described describe VBN 416 417 . . . 418 421 Th1 th1 NN 422 427 cells cell NNS 428 435 produce produce VBP 436 440 IL-2 il-2 NN 441 444 and and CC 445 454 IFN-gamma IFN-gamma NNP 454 455 , , , 456 463 whereas whereas IN 464 467 Th2 th2 NN 468 473 cells cell NNS 474 481 produce produce VBP 482 486 IL-4 il-4 NN 486 487 , , , 488 492 IL-5 IL-5 NNP 492 493 , , , 494 498 IL-6 IL-6 NNP 498 499 , , , 500 505 IL-10 IL-10 NNP 505 506 , , , 507 510 and and CC 511 516 IL-13 il-13 NN 516 517 . . . 518 520 In in IN 521 525 many many JJ 526 538 pathological pathological JJ 539 549 situations situation NNS 549 550 , , , 551 554 the the DT 555 562 balance balance NN 563 570 between between IN 571 574 Th1 th1 NN 575 578 and and CC 579 582 Th2 th2 NN 583 589 immune immune JJ 590 599 responses response NNS 600 610 determines determine VBZ 611 614 the the DT 615 622 outcome outcome NN 623 625 of of IN 626 633 diverse diverse JJ 634 649 immunologically immunologically RB 650 658 mediated mediate VBN 659 667 clinical clinical JJ 668 677 syndromes syndrome NNS 678 687 including include VBG 688 698 infectious infectious JJ 698 699 , , , 700 710 autoimmune autoimmune JJ 710 711 , , , 712 715 and and CC 716 724 allergic allergic JJ 725 733 diseases disease NNS 733 734 . . . 735 742 However however RB 742 743 , , , 744 747 the the DT 748 757 molecular molecular JJ 758 763 basis basis NN 764 767 for for IN 768 771 the the DT 772 787 tissue-specific tissue-specific JJ 788 798 expression expression NN 799 801 of of IN 802 814 Th1/Th2-like th1/th2-like JJ 815 824 cytokines cytokine NNS 825 828 has have VBZ 829 837 remained remain VBN 838 845 elusive elusive JJ 845 846 . . . 847 849 In in IN 850 854 this this DT 855 861 review review NN 862 864 we we PRP 865 873 evaluate evaluate VBP 874 877 the the DT 878 886 possible possible JJ 887 889 in in FW 890 894 vivo vivo FW 895 899 role role NN 900 902 of of IN 903 912 different different JJ 913 926 transcription transcription NN 927 934 factors factor NNS 935 938 and and CC 939 954 transcriptional transcriptional JJ 955 965 mechanisms mechanism NNS 966 968 in in IN 969 970 T t NN 971 975 cell cell NN 976 991 differentiation differentiation NN 992 995 and and CC 996 999 the the DT 1000 1006 immune immune JJ 1007 1015 response response NN 1015 1016 . . .