The molecular makeup and function of regulatory and effector synapses

Immunological Reviews

Volumn 218, Issue 1, 2007, Pages 165-177

  Reichardt, Peter ^a   Dornbach, Bastian ^a   Gunzer, Matthias ^a  

^a HELMHOLTZ CENTRE FOR INFECTION RESEARCH   (Germany)

Author keywords

B cell; Cell dynamics; Dendritic cell; Effector T cell; Immunological synapse; Regulatory T cell

Indexed keywords

CELL ADHESION MOLECULE; CYTOTOXIC T LYMPHOCYTE ANTIGEN 4; LYMPHOCYTE FUNCTION ASSOCIATED ANTIGEN 1;

B LYMPHOCYTE; CELL COMMUNICATION; CELL DIFFERENTIATION; CELL FUNCTION; CELL INTERACTION; CELL KINETICS; CELL LINE; CELL STRUCTURE; DENDRITIC CELL; EFFECTOR CELL; HUMAN; IMMUNE RESPONSE; IN VIVO STUDY; LYMPH NODE; NONHUMAN; PRIORITY JOURNAL; REVIEW; SYNAPSE; T LYMPHOCYTE; T LYMPHOCYTE ACTIVATION;

ANIMALS; ANTIGEN-PRESENTING CELLS; CELL COMMUNICATION; HUMANS; LYMPHOCYTE ACTIVATION; LYMPHOCYTES; SIGNAL TRANSDUCTION; SYNAPSES;

EID: 34447331260     PISSN: 01052896     EISSN: 1600065X     Source Type: Journal    
DOI: 10.1111/j.1600-065X.2007.00526.x     Document Type: Review

References (123)

1. Claman HN, Chaperon EA, Triplett RF. Immunocompetence of transferred thymus-marrow cell combinations. J Immunol 1966 97: 828 832.
2. Bromberg JS. The beginnings of T-B collaboration. J Immunol 2004 173: 7 13.
3. Steinman RM, Cohn ZA. Identification of a novel cell type in peripheral lymphoid organs of mice. I. Morphology, quantitation, tissue distribution. J Exp Med 1973 137: 1142 1162.
4. Steinman RM, Witmer MD. Lymphoid dendritic cells are potent stimulators of the primary mixed leukocyte reaction in mice. Proc Natl Acad Sci USA 1978 75: 5132 5136.
5. Meyer-Hermann ME, Maini PK. Interpreting two-photon imaging data of lymphocyte motility. Phys Rev E Stat Nonlin Soft Matter Phys 2005 71: 061912.
6. Reichardt P, Gunzer M. The biophysics of T lymphocyte activation in vitro and in vivo. In: Schraven B, Gundelfinger E, Seidenbecher C, eds. Cell Cell Communication in the Nervous and Immune System. Berlin: Springer-Verlag, 2006 199 218.
7. Miller MJ, Wei SH, Parker I, Cahalan MD. Two-photon imaging of lymphocyte motility and antigen response in intact lymph node. Science 2002 296: 1869 1873.
8. Miller MJ, Hejazi AS, Wei SH, Cahalan MD, Parker I. T cell repertoire scanning is promoted by dynamic dendritic cell behavior and random T cell motility in the lymph node. Proc Natl Acad Sci USA 2004 101: 998 1003.
9. Hedrick SM, Cohen DI, Nielsen EA, Davis MM. Isolation of cDNA clones encoding T cell-specific membrane-associated proteins. Nature 1984 308: 149 153.
10. Norcross MA, Bentley DM, Margulies DH, Germain RN. Membrane Ia expression and antigen-presenting accessory cell function of L cells transfected with class II major histocompatibility complex genes. J Exp Med 1984 160: 1316 1337.
11. Friedl P, den Boer AT, Gunzer M. Tuning immune responses: diversity and adaption of the immunological synapse. Nat Rev Immunol 2005 5: 532 545.
12. Mempel TR, Henrickson SE, von Andrian UH. T-cell priming by dendritic cells in lymph nodes occurs in three distinct phases. Nature 2004 427: 154 159.
13. Gunzer M, et al. Antigen presentation in extracellular matrix: interactions of T cells with dendritic cells are dynamic, short lived, and sequential. Immunity 2000 13: 323 332.
14. Norcross MA. A synaptic basis for T-lymphocyte activation. Ann Immunol (Paris) 1984 135D: 113 134.
15. Kupfer A, Swain SL, Janeway CA Jr., Singer SJ. The specific direct interaction of helper T cells and antigen-presenting B cells. Proc Natl Acad Sci USA 1986 83: 6080 6083.
16. Kupfer A, Singer SJ. The specific interaction of helper T cells and antigen-presenting B cells. IV. Membrane and cytoskeletal reorganizations in the bound T cell as a function of antigen dose. J Exp Med 1989 170: 1697 1713.
17. Kupfer A, Mosmann TR, Kupfer H. Polarized expression of cytokines in cell conjugates of helper T cells and splenic B cells. Proc Natl Acad Sci USA 1991 88: 775 779.
18. Kupfer H, Monks CR, Kupfer A. Small splenic B cells that bind to antigen-specific T helper (Th) cells and face the site of cytokine production in the Th cells selectively proliferate: immunofluorescence microscopic studies of Th-B antigen-presenting cell interactions. J Exp Med 1994 179: 1507 1515.
19. Monks CR, Freiberg BA, Kupfer H, Sciaky N, Kupfer A. Three-dimensional segregation of supramolecular activation clusters in T cells. Nature 1998 395: 82 86.
20. Grakoui A, et al. The immunological synapse: a molecular machine controlling T cell activation. Science 1999 285: 221 227.
21. Iezzi G, Karjalainen K, Lanzavecchia A. The duration of antigenic stimulation determines the fate of naive and effector T cells. Immunity 1998 8: 89 95.
22. Dustin ML, Bromley SK, Kan A, Peterson DA, Unanue ER. Antigen receptor engagement delivers a stop signal to migrating T lymphocytes. Proc Natl Acad Sci USA 1997 94: 3909 3913.
23. Lanzavecchia A, Iezzi G, Viola A. From TCR engagement to T cell activation: a kinetic view of T cell behavior. Cell 1999 96: 1 4.
24. Dustin ML, Cooper JA. The immunological synapse and the actin cytoskeleton: molecular hardware for T cell signaling. Nat Immunol 2000 1: 23 29.
25. Underhill DM, Bassetti M, Rudensky A, Aderem A. Dynamic interactions of macrophages with T cells during antigen presentation. J Exp Med 1999 190: 1909 1914.
26. Faroudi M, Zaru R, Paulet P, Müller S, Valitutti S. Cutting edge: T lymphocyte activation by repeated immunological synapse formation and intermittent signaling. J Immunol 2003 171: 1128 1132.
27. Brossard C, et al. Multifocal structure of the T cell - dendritic cell synapse. Eur J Immunol 2005 35: 1741 1753.
28. Lee KH, Holdorf AD, Dustin ML, Chan AC, Allen PM, Shaw AS. T cell receptor signaling precedes immunological synapse formation. Science 2002 295: 1539 1542.
29. Lee KH, et al. The immunological synapse balances T cell receptor signaling and degradation. Science 2003 302: 1218 1222.
30. Yokosuka T, et al. Newly generated T cell receptor microclusters initiate and sustain T cell activation by recruitment of Zap70 and SLP-76. Nat Immunol 2005 6: 1253 1262.
31. Campi G, Varma R, Dustin ML. Actin and agonist MHC-peptide complex-dependent T cell receptor microclusters as scaffolds for signaling. J Exp Med 2005 202: 1031 1036.
32. Varma R, Campi G, Yokosuka T, Saito T, Dustin ML. T cell receptor-proximal signals are sustained in peripheral microclusters and terminated in the central supramolecular activation cluster. Immunity 2006 25: 117 127.
33. Figge MT, Meyer-Hermann M. Geometrically repatterned immunological synapses uncover formation mechanisms. PLoS Comput Biol 2006 2: e171.
34. Miller MJ, Safrina O, Parker I, Cahalan MD. Imaging the single cell dynamics of CD4+ T cell activation by dendritic cells in lymph nodes. J Exp Med 2004 200: 847 856.
35. Stoll S, Delon J, Brotz TM, Germain RN. Dynamic imaging of T cell-dendritic cell interactions in lymph nodes. Science 2002 296: 1873 1876.
36. Shakhar G, et al. Stable T cell-dendritic cell interactions precede the development of both tolerance and immunity in vivo. Nat Immunol 2005 6: 707 714.
37. Delon J, Bercovici N, Raposo G, Liblau R, Trautmann A. Antigen-dependent and -independent Ca2+ responses triggered in T cells by dendritic cells compared with B cells. J Exp Med 1998 188: 1473 1484.
38. Barcia C, et al. In vivo mature immunological synapses forming SMACs mediate clearance of virally infected astrocytes from the brain. J Exp Med 2006 203: 2095 2107.
39. Matsui K, Boniface JJ, Steffner P, Reay PA, Davis MM. Kinetics of T-cell receptor binding to peptide/I-Ekcomplexes: correlation of the dissociation rate with T-cell responsiveness. Proc Natl Acad Sci USA 1994 91: 12862 12866.
40. Alam SM, et al. T-cell-receptor affinity and thymocyte positive selection. Nature 1996 381: 616 620.
41. McKeithan TW. Kinetic proofreading in T-cell receptor signal transduction. Proc Natl Acad Sci USA 1995 92: 5042 5046.
42. Valitutti S, Müller S, Cella M, Padovan E, Lanzavecchia A. Serial triggering of many T-cell receptors by a few peptide-MHC complexes. Nature 1995 375: 148 151.
43. Rabinowitz JD, Beeson C, Lyons DS, Davis MM, McConnell HM. Kinetic discrimination in T-cell activation. Proc Natl Acad Sci USA 1996 93: 1401 1405.
44. Kersh GJ, Kersh EN, Fremont DH, Allen PM. High- and low-potency ligands with similar affinities for the TCR: the importance of kinetics in TCR signaling. Immunity 1998 9: 817 826.
45. Stefanova II., Hemmer B, Vergelli M, Martin R, Biddison WE, Germain RN. TCR ligand discrimination is enforced by competing ERK positive and SHP-1 negative feedback pathways. Nat Immunol 2003 4: 248 254.
46. Viola A, Lanzavecchia A. T cell activation determined by T cell receptor number and tunable thresholds. Science 1996 273: 104 106.
47. Yachi PP, Ampudia J, Zal T, Gascoigne NR. Altered peptide ligands induce delayed CD8-T cell receptor interaction - a role for CD8 in distinguishing antigen quality. Immunity 2006 25: 203 211.
48. McNeil LK, Evavold BD. Dissociation of peripheral T cell responses from thymocyte negative selection by weak agonists supports a spare receptor model of T cell activation. Proc Natl Acad Sci USA 2002 99: 4520 4525.
49. Labrecque N, Whitfield LS, Obst R, Waltzinger C, Benoist C, Mathis D. How much TCR does a T cell need? Immunity 2001 15: 71 82.
50. Irvine DJ, Purbhoo MA, Krogsgaard M, Davis MM. Direct observation of ligand recognition by T cells. Nature 2002 419: 845 849.
51. Monks CR, Kupfer H, Tamir I, Barlow A, Kupfer A. Selective modulation of protein kinase C-theta during T-cell activation. Nature 1997 385: 83 86.
52. Depoil D, et al. Immunological synapses are versatile structures enabling selective T cell polarization. Immunity 2005 22: 185 194.
53. Wulfing C, Sumen C, Sjaastad MD, Wu LC, Dustin ML, Davis MM. Costimulation and endogenous MHC ligands contribute to T cell recognition. Nat Immunol 2002 3: 42 47.
54. Krogsgaard M, Li QJ, Sumen C, Huppa JB, Huse M, Davis MM. Agonist/endogenous peptide-MHC heterodimers drive T cell activation and sensitivity. Nature 2005 434: 238 243.
55. Banchereau J, Steinman RM. Dendritic cells and the control of immunity. Nature 1998 392: 245 254.
56. Fuchs EJ, Matzinger P. B cells turn off virgin but not memory T cells. Science 1992 258: 1156 1159.
57. Germain RN, Jenkins MK. In vivo antigen presentation. Curr Opin Immunol 2004 16: 120 125.
58. Byersdorfer CA, Dipaolo RJ, Petzold SJ, Unanue ER. Following immunization antigen becomes concentrated in a limited number of APCs including B cells. J Immunol 2004 173: 6627 6634.
59. Zhong G, Reis e Sousa C, Germain RN. Antigen-unspecific B cells and lymphoid dendritic cells both show extensive surface expression of processed antigen-major histocompatibility complex class II complexes after soluble protein exposure in vivo or in vitro. J Exp Med 1997 186: 673 682.
60. Rodriguez-Pinto D, Moreno J. B cells can prime naive CD4(+) T cells in vivo in the absence of other professional antigen-presenting cells in a CD154-CD40-dependent manner. Eur J Immunol 2005 35: 1097 1105.
61. Epstein MM, Di RF, Jankovic D, Sher A, Matzinger P. Successful T cell priming in B cell-deficient mice. J Exp Med 1995 182: 915 922.
62. Lassila O, Vainio O, Matzinger P. Can B cells turn on virgin T cells? Nature 1988 334: 253 255.
63. Gunzer M, et al. A spectrum of biophysical interaction modes between T cells and different antigen presenting cells during priming in 3-D collagen and in vivo. Blood 2004 104: 2801 2809.
64. Crawford A, Macleod M, Schumacher T, Corlett L, Gray D. Primary T cell expansion and differentiation in vivo requires antigen presentation by B cells. J Immunol 2006 176: 3498 3506.
65. Okada T, et al. Antigen-engaged B cells undergo chemotaxis toward the T zone and form motile conjugates with helper T cells. PLoS Biol 2005 3: e150.
66. Richie LI, Ebert PJ, Wu LC, Krummel MF, Owen JJ, Davis MM. Imaging synapse formation during thymocyte selection: inability of CD3zeta to form a stable central accumulation during negative selection. Immunity 2002 16: 595 606.
67. Lettau M, et al. The adaptor protein Nck interacts with Fas ligand: guiding the death factor to the cytotoxic immunological synapse. Proc Natl Acad Sci USA 2006 103: 5911 5916.
68. Trambas CM, Griffiths GM. Delivering the kiss of death. Nat Immunol 2003 4: 399 403.
69. O'Keefe JP, Blaine K, Alegre ML, Gajewski TF. Formation of a central supramolecular activation cluster is not required for activation of naive CD8+ T cells. Proc Natl Acad Sci USA 2004 101: 9351 9356.
70. Purbhoo MA, Irvine DJ, Huppa JB, Davis MM. T cell killing does not require the formation of a stable mature immunological synapse. Nat Immunol 2004 5: 524 530.
71. Mosmann TR, Cherwinski H, Bond MW, Giedlin MA, Coffman RL. Two types of murine helper T cell clone. I. Definition according to profiles of lymphokine activities and secreted proteins. J Immunol 1986 136: 2348 2357.
72. Maldonado RA, Irvine DJ, Schreiber R, Glimcher LH. A role for the immunological synapse in lineage commitment of CD4 lymphocytes. Nature 2004 431: 527 532.
73. Hwang JM, Yamanouchi J, Santamaria P, Kubes P. A critical temporal window for selectin-dependent CD4+ lymphocyte homing and initiation of late-phase inflammation in contact sensitivity. J Exp Med 2004 199: 1223 1234.
74. Galkina E, et al. L-selectin shedding does not regulate constitutive T cell trafficking but controls the migration pathways of antigen-activated T lymphocytes. J Exp Med 2003 198: 1323 1335.
75. von Andrian UH, Mempel TR. Homing and cellular traffic in lymph nodes. Nat Rev Immunol 2003 3: 867 878.
76. Sallusto F, Geginat J, Lanzavecchia A. Central memory and effector memory T cell subsets: function, generation, and maintenance. Annu Rev Immunol 2004 22: 745 763.
77. Lechner O, Lauber J, Franzke A, Sarukhan A, von Boehmer H, Buer J. Fingerprints of anergic T cells. Curr Biol 2001 11: 587 595.
78. Sloan-Lancaster J, Shaw AS, Rothbard JB, Allen PM. Partial T cell signaling: altered phospho-zeta and lack of zap70 recruitment in APL-induced T cell anergy. Cell 1994 79: 913 922.
79. Hundt M, et al. Impaired activation and localization of LAT in anergic T cells as a consequence of a selective palmitoylation defect. Immunity 2006 24: 513 522.
80. Zambricki E, et al. In vivo anergized T cells form altered immunological synapses in vitro. Am J Transplant 2006 6: 2572 2579.
81. Sakaguchi S. Regulatory T cells: key controllers of immunologic self-tolerance. Cell 2000 101: 455 458.
82. von Boehmer H. Dynamics of suppressor T cells: in vivo veritas. J Exp Med 2003 198: 845 849.
83. Apostolou I, Sarukhan A, Klein L, von Boehmer H. Origin of regulatory T cells with known specificity for antigen. Nat Immunol 2002 3: 756 763.
84. Jonuleit H, Schmitt E, Schuler G, Knop J, Enk AH. Induction of interleukin 10-producing, nonproliferating CD4(+) T cells with regulatory properties by repetitive stimulation with allogeneic immature human dendritic cells. J Exp Med 2000 192: 1213 1222.
85. Sumoza-Toledo A, Eaton AD, Sarukhan A. Regulatory T cells inhibit protein kinase C theta recruitment to the immune synapse of naive T cells with the same antigen specificity. J Immunol 2006 176: 5779 5787.
86. Sun Z, et al. PKC-theta is required for TCR-induced NF-kappaB activation in mature but not immature T lymphocytes. Nature 2000 404: 402 407.
87. Bi K, et al. Antigen-induced translocation of PKC-straight theta to membrane rafts is required for T cell activation. Nat Immunol 2001 2: 556 563.
88. Ise W, et al. Orally tolerized T cells can form conjugates with APCs but are defective in immunological synapse formation. J Immunol 2005 175: 829 838.
89. Dustin ML, Tseng SY, Varma R, Campi G. T cell-dendritic cell immunological synapses. Curr Opin Immunol 2006 18: 512 516.
90. Li QJ, et al. CD4 enhances T cell sensitivity to antigen by coordinating Lck accumulation at the immunological synapse. Nat Immunol 2004 5: 791 799.
91. Serrador JM, Cabrero JR, Sancho D, Mittelbrunn M, Urzainqui A, Sanchez-Madrid F. HDAC6 deacetylase activity links the tubulin cytoskeleton with immune synapse organization. Immunity 2004 20: 417 428.
92. Freiberg BA, et al. Staging and resetting T cell activation in SMACs. Nat Immunol 2002 3: 911 917.
93. Shiow LR, et al. CD69 acts downstream of interferon-alpha/beta to inhibit S1P1 and lymphocyte egress from lymphoid organs. Nature 2006 440: 540 544.
94. Hofer S, et al. Dendritic cells regulate T-cell deattachment through the integrin-interacting protein CYTIP. Blood 2006 107: 1003 1009.
95. Horejsi V, Zhang W, Schraven B. Transmembrane adaptor proteins: organizers of immunoreceptor signalling. Nat Rev Immunol 2004 4: 603 616.
96. Holdorf AD, Lee KH, Burack WR, Allen PM, Shaw AS. Regulation of Lck activity by CD4 and CD28 in the immunological synapse. Nat Immunol 2002 3: 259 264.
97. Krause M, Sechi AS, Konradt M, Monner D, Gertler FB, Wehland J. Fyn-binding protein (Fyb)/SLP-76-associated protein (SLAP), Ena/vasodilator- stimulated phosphoprotein (VASP) proteins and the Arp2/3 complex link T cell receptor (TCR) signaling to the actin cytoskeleton. J Cell Biol 2000 149: 181 194.
98. Jo EK, Wang H, Rudd CE. An essential role for SKAP-55 in LFA-1 clustering on T cells that cannot be substituted by SKAP-55R. J Exp Med 2005 201: 1733 1739.
99. Stradal TE, Rottner K, Disanza A, Confalonieri S, Innocenti M, Scita G. Regulation of actin dynamics by WASP and WAVE family proteins. Trends Cell Biol 2004 14: 303 311.
100. Costello PS, Gallagher M, Cantrell DA. Sustained and dynamic inositol lipid metabolism inside and outside the immunological synapse. Nat Immunol 2002 3: 1082 1089.
101. Lewis RS. Calcium signaling mechanisms in T lymphocytes. Annu Rev Immunol 2001 19: 497 521.
102. Ostrov DA, Shi W, Schwartz JC, Almo SC, Nathenson SG. Structure of murine CTLA-4 and its role in modulating T cell responsiveness. Science 2000 290: 816 819.
103. Pentcheva-Hoang T, Egen JG, Wojnoonski K, Allison JP. B7-1 and b7-2 selectively recruit ctla-4 and CD28 to the immunological synapse. Immunity 2004 21: 401 413.
104. Schneider H, Valk E, da Rocha DS, Wei B, Rudd CE. CTLA-4 up-regulation of lymphocyte function-associated antigen 1 adhesion and clustering as an alternate basis for coreceptor function. Proc Natl Acad Sci USA 2005 102: 12861 12866.
105. Dillon TJ, Carey KD, Wetzel SA, Parker DC, Stork PJ. Regulation of the small GTPase Rap1 and extracellular signal-regulated kinases by the costimulatory molecule CTLA-4. Mol Cell Biol 2005 25: 4117 4128.
106. Stork PJ, Dillon TJ. Multiple roles of Rap1 in hematopoietic cells: complementary versus antagonistic functions. Blood 2005 106: 2952 2961.
107. Ishida D, et al. Antigen-driven T cell anergy and defective memory T cell response via deregulated Rap1 activation in SPA-1-deficient mice. Proc Natl Acad Sci USA 2003 100: 10919 10924.
108. Sebzda E, Bracke M, Tugal Y, Hogg N, Cantrell DA. Rap1A positively regulates T cells via integrin activation rather than inhibiting lymphocyte signaling. Nat Immunol 2002 3: 251 258.
109. Katagiri K, Maeda A, Shimonaka M, Kinashi T. RAPL, a Rap1-binding molecule that mediates Rap1-induced adhesion through spatial regulation of LFA-1. Nat Immunol 2003 4: 741 748.
110. Nashar TO, Drake JR. Dynamics of MHC class II-activating signals in murine resting B cells. J Immunol 2006 176: 827 838.
111. Kolanus W, et al. Alpha L beta 2 integrin/LFA-1 binding to ICAM-1 induced by cytohesin-1, a cytoplasmic regulatory molecule. Cell 1996 86: 233 242.
112. Geiger C, et al. Cytohesin-1 regulates beta-2 integrin-mediated adhesion through both ARF-GEF function and interaction with LFA-1. EMBO J 2000 19: 2525 2536.
113. Boehm T, et al. Attenuation of cell adhesion in lymphocytes is regulated by CYTIP, a protein which mediates signal complex sequestration. EMBO J 2003 22: 1014 1024.
114. Bousso P, Robey E. Dynamics of CD8(+) T cell priming by dendritic cells in intact lymph nodes. Nat Immunol 2003 4: 579 585.
115. Labeur MS, Roters B, Pers B, Mehling A, Luger TA, Schwarz T, Grabbe S. Generation of tumor immunity by bone marrow-derived dendritic cells correlates with dendritic cell maturation stage. J Immunol 1999 162: 168 175.
116. Carey KD, et al. CD28 and the tyrosine kinase lck stimulate mitogen-activated protein kinase activity in T cells via inhibition of the small G protein Rap1. Mol Cell Biol 2000 20: 8409 8419.
117. Delon J, Bercovici N, Liblau R, Trautmann A. Imaging antigen recognition by naive CD4+ T cells: compulsory cytoskeletal alterations for the triggering of an intracellular calcium response. Eur J Immunol 1998 28: 716 729.
118. Scheffold A, Assenmacher M, Reiners-Schramm L, Lauster R, Radbruch A. High-sensitivity immunofluorescence for detection of the pro- and anti-inflammatory cytokines gamma interferon and interleukin-10 on the surface of cytokine-secreting cells. Nat Med 2000 6: 107 110.
119. Egen JG, Allison JP. Cytotoxic T lymphocyte antigen-4 accumulation in the immunological synapse is regulated by TCR signal strength. Immunity 2002 16: 23 35.
120. Jago CB, Yates J, Camara NO, Lechler RI, Lombardi G. Differential expression of CTLA-4 among T cell subsets. Clin Exp Immunol 2004 136: 463 471.
121. Schneider H, et al. Reversal of the TCR stop signal by CTLA-4. Science 2006 313: 1972 1975.
122. Huppa JB, Gleimer M, Sumen C, Davis MM. Continuous T cell receptor signaling required for synapse maintenance and full effector potential. Nat Immunol 2003 4: 749 755.
123. Reichardt P, et al. Naive B cells generate regulatory T cells in the presence of a mature immunological synapse. Blood 2007 in Press.