Nanoscale Increases in CD2-CD48-mediated Intermembrane Spacing Decrease Adhesion and Reorganize the Immunological Synapse

The relationship between intermembrane spacing, adhesion efficiency, and lateral organization of adhesion receptors has not been established for any adhesion system. We have utilized the CD2 ligand CD48 with two (wild type CD48 (CD48-WT)), four (CD48-CD2), or five (CD48-CD22) Ig-like domains. CD48-WT was 10-fold more efficient in mediating adhesion than CD48-CD2 or CD48-CD22. Electron tomography of contact areas with planar bilayers demonstrated average intermembrane spacing of 12.8 nm with CD48-WT, 14.7 nm with CD48-CD2, and 15.6 nm with CD48-CD22. Both CD48-CD2 and CD48-CD22 chimeras segregated completely from CD48-WT in mixed contact areas. In contrast, CD48-CD2 and CD48-CD22 co-localized when mixed contacts were formed. Confocal imaging of immunological synapses formed between primary T lymphocytes and Chinese hamster ovary cells presenting major histocompatibility complex-peptide complexes, and different forms of CD48 demonstrated that CD48-CD2 and CD48-CD22 induce an eccentric CD2/T cell antigen receptor cluster. We propose that this reorganization of the immunological synapse sequesters the T cell antigen receptor in a location where it cannot interact with its ligand and dramatically reduces T cell sensitivity. The relationship between intermembrane spacing, adhesion efficiency, and lateral organization of adhesion receptors has not been established for any adhesion system. We have utilized the CD2 ligand CD48 with two (wild type CD48 (CD48-WT)), four (CD48-CD2), or five (CD48-CD22) Ig-like domains. CD48-WT was 10-fold more efficient in mediating adhesion than CD48-CD2 or CD48-CD22. Electron tomography of contact areas with planar bilayers demonstrated average intermembrane spacing of 12.8 nm with CD48-WT, 14.7 nm with CD48-CD2, and 15.6 nm with CD48-CD22. Both CD48-CD2 and CD48-CD22 chimeras segregated completely from CD48-WT in mixed contact areas. In contrast, CD48-CD2 and CD48-CD22 co-localized when mixed contacts were formed. Confocal imaging of immunological synapses formed between primary T lymphocytes and Chinese hamster ovary cells presenting major histocompatibility complex-peptide complexes, and different forms of CD48 demonstrated that CD48-CD2 and CD48-CD22 induce an eccentric CD2/T cell antigen receptor cluster. We propose that this reorganization of the immunological synapse sequesters the T cell antigen receptor in a location where it cannot interact with its ligand and dramatically reduces T cell sensitivity. T cell activation requires interactions of T cell antigen receptors (TCRs) 2The abbreviations used are: TCR, T cell receptor; cSMAC, central supramolecular activation cluster; ICAM, intercellular adhesion molecule; IS, immunological synapse; LFA, lymphocyte function-associated antigen; MCC, moth cytochrome c; MHC, major histocompatibility complex; MHCp, MHC-peptide; CD48-WT, wild type CD48; FITC, fluorescein isothiocyanate; APC, antigen-presenting cell; CHO, Chinese hamster ovary. 2The abbreviations used are: TCR, T cell receptor; cSMAC, central supramolecular activation cluster; ICAM, intercellular adhesion molecule; IS, immunological synapse; LFA, lymphocyte function-associated antigen; MCC, moth cytochrome c; MHC, major histocompatibility complex; MHCp, MHC-peptide; CD48-WT, wild type CD48; FITC, fluorescein isothiocyanate; APC, antigen-presenting cell; CHO, Chinese hamster ovary. with peptide-presenting major histocompatibility complexes (MHCp), which are anchored to the plasma membrane of the T cell and antigen-presenting cells, respectively (1Garcia K.C. Degano M. Stanfield R.L. Brunmark A. Jackson M.R. Peterson P.A. Teyton L. Wilson I.A. Science. 1996; 274: 209-219Crossref PubMed Scopus (1052) Google Scholar, 2Dustin M.L. Bromley S.K. Davis M.M. Zhu C. Annu. Rev. Cell Dev. Biol. 2001; 17: 133-157Crossref PubMed Scopus (125) Google Scholar). Adhesion molecule pairs facilitate this process by physically holding the cells together and providing additional signals that are integrated by the T cell (3Springer T.A. Nature. 1990; 346: 425-434Crossref PubMed Scopus (5816) Google Scholar, 4Weiss A. Littman D.R. Cell. 1994; 76: 263-274Abstract Full Text PDF PubMed Scopus (1941) Google Scholar). Adhesion molecules that participate in T cell activation can be categorized into at least two groups: the integrin family adhesion molecules that include lymphocyte function-associated antigen (LFA)-1 on T cells, which interacts with intercellular adhesion molecule (ICAM)-1 on antigen-presenting cells, and the small immunoglobulin superfamily molecules like CD2 on T cells, which interacts with CD48 on the surface of antigen-presenting cells (3Springer T.A. Nature. 1990; 346: 425-434Crossref PubMed Scopus (5816) Google Scholar, 5Kato K. Koyanagi M. Okada H. Takanashi T. Wong Y.W. Williams A.F. Okumura K. Yagita H. J. Exp. Med. 1992; 176: 1241-1249Crossref PubMed Scopus (215) Google Scholar). Adhesion molecules and TCR are organized in an immunological synapse (IS) (6Monks C.R. Freiberg B.A. Kupfer H. Sciaky N. Kupfer A. Nature. 1998; 395: 82-86Crossref PubMed Scopus (1945) Google Scholar, 7Dustin M.L. Olszowy M.W. Holdorf A.D. Li J. Bromley S. Desai N. Widder P. Rosenberger F. van der Merwe P.A. Allen P.M. Shaw A.S. Cell. 1998; 94: 667-677Abstract Full Text Full Text PDF PubMed Scopus (582) Google Scholar). Supported planar bilayers containing ICAM-1 and MHCp reconstitute formation of the IS (8Grakoui A. Bromley S.K. Sumen C. Davis M.M. Shaw A.S. Allen P.M. Dustin M.L. Science. 1999; 285: 221-227Crossref PubMed Scopus (2512) Google Scholar). This model IS is characterized by a bull's eye-like configuration of a central supramolecular activation complex (cSMAC) enriched in TCR, a peripheral supramolecular activation complex enriched in LFA-1, and a distal supramolecular activation complex enriched in CD45 and F-actin (9Freiberg B.A. Kupfer H. Maslanik W. Delli J. Kappler J. Zaller D.M. Kupfer A. Nat. Immunol. 2002; 3: 911-917Crossref PubMed Scopus (277) Google Scholar). The distal supramolecular activation complex is essentially a radial lamellipodium (10Sims T.N. Soos T.J. Xenias H.S. Dubin-Thaler B. Hofman J.M. Waite J.C. Cameron T.O. Thomas V.K. Varma R. Wiggins C.H. Sheetz M.P. Littman D.R. Dustin M.L. Cell. 2007; 129: 773-785Abstract Full Text Full Text PDF PubMed Scopus (269) Google Scholar) that is the site of nucleation of segregated TCR and LFA-1 microclusters that are transported by centripetal actin flow to the cSMAC via the peripheral supramolecular activation complex (11Varma R. Campi G. Yokosuka T. Saito T. Dustin M.L. Immunity. 2006; 25: 117-127Abstract Full Text Full Text PDF PubMed Scopus (649) Google Scholar, 12Kaizuka Y. Douglass A.D. Varma R. Dustin M.L. Vale R.D. Proc. Natl. Acad. Sci. U. S. A. 2007; 51: 20296-20301Crossref Scopus (285) Google Scholar). Signaling in TCR microclusters takes place during this transport process, and signaling is inactivated in the cSMAC (11Varma R. Campi G. Yokosuka T. Saito T. Dustin M.L. Immunity. 2006; 25: 117-127Abstract Full Text Full Text PDF PubMed Scopus (649) Google Scholar, 13Campi G. Varma R. Dustin M.L. J. Exp. Med. 2005; 202: 1031-1036Crossref PubMed Scopus (452) Google Scholar, 14Yokosuka T. Sakata-Sogawa K. Kobayashi W. Hiroshima M. Hashimoto-Tane A. Tokunaga M. Dustin M.L. Saito T. Nat. Immunol. 2005; 6: 1253-1262Crossref PubMed Scopus (549) Google Scholar). The mechanism by which TCR and LFA-1 initially segregate is not known. Springer (3Springer T.A. Nature. 1990; 346: 425-434Crossref PubMed Scopus (5816) Google Scholar) speculated that receptor size could lead to segregation of LFA-1 from TCR in a contact area. LFA-1, like other integrins, is a large noncovalent transmembrane heterodimer and undergoes dramatic conformational changes leading to extension of ∼28 nm from the membrane surface (15Takagi J. Petre B.M. Walz T. Springer T.A. Cell. 2002; 110: 599-611Abstract Full Text Full Text PDF PubMed Scopus (907) Google Scholar). ICAM-1 is also a relatively long molecule predicted to project ∼18 nm from the surface (16Staunton D.E. Marlin S.D. Stratowa C. Dustin M.L. Springer T.A. Cell. 1988; 52: 925-933Abstract Full Text PDF PubMed Scopus (797) Google Scholar). The TCR and MHCp project about 7.5 nm from the surface each and are predicted to interact across an intermembrane distance of ∼13 nm (1Garcia K.C. Degano M. Stanfield R.L. Brunmark A. Jackson M.R. Peterson P.A. Teyton L. Wilson I.A. Science. 1996; 274: 209-219Crossref PubMed Scopus (1052) Google Scholar). The interaction of CD2 with CD48 generates a complex that is also ∼13 nm long, as was first suggested by mutagenesis and modeling studies (17van der Merwe P.A. McNamee P.N. Davies E.A. Barclay A.N. Davis S.J. Curr. Biol. 1995; 5: 74-84Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar) and later confirmed in structural studies (18Wang J.H. Smolyar A. Tan K. Liu J.H. Kim M. Sun Z.Y. Wagner G. Reinherz E.L. Cell. 1999; 97: 791-803Abstract Full Text Full Text PDF PubMed Scopus (197) Google Scholar). The CD2-CD58 interaction segregates from the LFA-1-ICAM-1 interaction in sites of adhesion, but it is not clear if this is due to size differences or to differential membrane and cytoskeletal interactions (7Dustin M.L. Olszowy M.W. Holdorf A.D. Li J. Bromley S. Desai N. Widder P. Rosenberger F. van der Merwe P.A. Allen P.M. Shaw A.S. Cell. 1998; 94: 667-677Abstract Full Text Full Text PDF PubMed Scopus (582) Google Scholar). The manner in which apparent molecular size, actual intermembrane spacing, and lateral organization are related is not clear. Linear assumptions can be misleading, based on tomography studies of in which of molecules is W. P. Science. PubMed Scopus Google Scholar, A. A.S. Nature. 2007; PubMed Scopus Google Scholar). of signaling and adhesion has been to the CD2 can lead to T cell activation in a manner of the TCR Dustin M. Springer T.A. A. J. Immunol. 1988; Google Scholar). CD2 has a large that activation of the family A.D. J.M. S.D. Allen P.M. Shaw A.S. J. Exp. Med. 1999; PubMed Scopus Google Scholar). CD2 is to sites of TCR in the of ligand A.D. Vale R.D. Cell. 2005; Full Text Full Text PDF PubMed Scopus Google Scholar, M. R. P. S. S. J. Immunol. PubMed Scopus Google Scholar). type CD48 has two Ig-like and T cell activation when on which are for the of two or (CD48-CD22) additional Ig-like T cell activation mediating adhesion A. Davies E.A. H. Saito T. van der Merwe P.A. J. Exp. Med. 1999; PubMed Scopus Google Scholar). The of forms of CD48 on adhesion efficiency, the intermembrane organization of contact or the of the IS have not been that four Ig-like to a structural of the average intermembrane by nm K. K. van der Merwe P.A. Nature. 2005; PubMed Scopus Google Scholar). In this a of CD48-WT, CD48-CD2, and CD48-CD22 for of cell adhesion, intermembrane lateral and organization of the the planar were to the of ligand the of CD48 its as an adhesion by 10-fold and the intermembrane by were two in mixed in which the of CD2 ligand dramatically or by the and in which each in membrane domains. of Ig-like to and differences of of CD48-CD2 or CD48-CD22 on the antigen-presenting cell T cell of antigen and of the immunological and cell CD48-WT, CD48-CD2, and CD48-CD22 were A. Davies E.A. H. Saito T. van der Merwe P.A. J. Exp. Med. 1999; PubMed Scopus Google Scholar). forms were from of cells as M.L. D.E. Zhu D.M. J.M. W. Davies E.A. van der Merwe P.A. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). and T Cell were in with and from TCR were by the of moth cytochrome to T cell as (8Grakoui A. Bromley S.K. Sumen C. Davis M.M. Shaw A.S. Allen P.M. Dustin M.L. Science. 1999; 285: 221-227Crossref PubMed Scopus (2512) Google Scholar). T Cell and Cell by were as Liu M. Dustin M.L. J. Immunol. 2005; PubMed Scopus Google Scholar). T cells were from by The cells were with for the cells were in and with was based on the of cells that at least and cytochrome cells were to in which were with T cells for at and with was as and were with a Liu M. Dustin M.L. J. Immunol. 2005; PubMed Scopus Google Scholar). of at a to include the were in and were from into the and were in CD2 and TCR were as in when than the Electron were by the of a and in and for at on planar bilayers were and as Dustin M.L. Springer T.A. J. Cell Biol. PubMed Scopus Google Scholar). for tomography were at with a size of nm an at Electron The and a from to with at were and were a by and H. 2006; PubMed Scopus Google Scholar). between the of the and the of the lymphocyte plasma membrane were in by a at contact areas and the This in the distance to the K. Koyanagi M. Okada H. Takanashi T. Wong Y.W. Williams A.F. Okumura K. Yagita H. J. Exp. Med. 1992; 176: 1241-1249Crossref PubMed Scopus (215) Google and were used for flow was with CD2 and were used in was by A. E.A. V.K. Cell. Immunol. 2001; PubMed Scopus Google Scholar). was by with and into with a of The of CD48 in the bilayers was by bilayers on with of and on a flow for Supported planar bilayers were in a flow cell was on a with an and M.L. D.E. Zhu D.M. J.M. W. Davies E.A. van der Merwe P.A. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar, M.L. T. Varma R. Thomas V.K. W. in and Scholar). were with a Electron were a IS were by of a was used to cell to the and differences were when was than CD48 Adhesion the of CD48 on adhesion, used planar bilayers containing and CD48-WT, CD48-CD2, or CD48-CD22 at different and the adhesion of T cell by contact areas by a of T cells were to interact with bilayers for at which is for adhesion by forms to CD48-WT adhesion at CD48-CD2 or CD48-CD22 to adhesion The in adhesion between CD48-WT and CD48-CD2 or CD48-CD22 was at and The between CD48-CD2 and CD48-CD22 was not with contact areas for CD48-WT and CD48-CD22 that the CD48-WT is more efficient at mediating adhesion than of Electron on by CD48-WT or of of the size of CD48 on intermembrane spacing was by T cell were to to planar bilayers containing of CD48-WT or of CD48-CD2 or CD48-CD22 to The cells were and to tomography and for of the intermembrane distance to the planar for CD48-WT and CD48-CD22 are in assumptions lead to a of the in intermembrane spacing was to based on intermembrane of 12.8 nm for CD48-WT, 14.7 for CD48-CD2, and 15.6 nm for CD48-CD22 between were at were in contacts with interactions K. K. van der Merwe P.A. Nature. 2005; PubMed Scopus Google Scholar). on in the any lateral segregation of interactions from the in intermembrane spacing T cell were to to bilayers containing and or or each In the molecular of the CD48 was to an of adhesion, for CD48-WT and for CD48-CD2 or CD48-CD22. The interaction of CD2 with CD48 was as T cells with bilayers CD48-WT or CD48-CD22 a of the CD48 the of with of in CD48-WT than CD48-CD22 T cells with bilayers of CD48-WT with CD48-CD22 at adhesion, were in the contact in of contacts formed the interactions were the of CD48-WT was by the of contact areas that CD48-WT CD48-CD22 to at the of the mixed which were to when the of CD48-WT was by the of contacts that CD48-CD22 CD48-WT to and mixed contacts were mixed contact areas are formed in a relatively of of the of CD48-WT, CD48-CD2, and CD48-CD22 in contact areas that each to with and of the segregated in mixed contacts that the of ligand in the mixed contacts was of the contacts for CD48-CD22 but was of the contacts for CD48-WT the of a the contact that the between were place in an of with the of the imaging that the actual between are by a of nm between areas of and CD48-CD2 and CD48-CD22 were in a at at which an adhesion the CD48-CD22 interaction was more than the CD48-CD2 of contact areas of and segregation in the the of CD48-CD2 by with the the of CD48-CD22 by based on on This was that based on adhesion and that segregate based on the size The that a is not to induce segregation and that for the CD48-CD22 molecules have an the CD48-CD2 molecules in for to cell surface of the CD48 on T A. Davies E.A. H. Saito T. van der Merwe P.A. J. Exp. Med. 1999; PubMed Scopus Google Scholar) demonstrated that forms of CD48 of antigen by T cell T cell not organized to the of forms of CD48 on primary T cells, which organized The of the of the interaction was primary T cells as and a of cell as A. Davies E.A. H. Saito T. van der Merwe P.A. J. Exp. Med. 1999; PubMed Scopus Google Scholar). T cells are by a from in the of the molecule cell and of forms of CD48 at The surface of cells was not the of on the surface of the cells is This be to adhesion for forms of based on the planar The of CD48 on T cell activation was by in primary T T cells were from of and T cells were T cells were with and with CD48 or cells in the of different of and the of cells was used to with the CD48-WT more than CD48 This was the of used but was at cells with the CD48 forms with The CD48-CD22 was a more than This was at which of IS The major molecule on cells is ICAM-1 A. E.A. V.K. Cell. Immunol. 2001; PubMed Scopus Google Scholar). on the with We that in the of LFA-1-ICAM-1 CD48-WT was at T cell In the of the LFA-1-ICAM-1 the cells than the CD48 cells, and CD48-CD22 was In the adhesion, the forms of CD48 as adhesion and on a more that forms of CD48 are when in the of an and CD48 and CD2 CD48 molecular in the IS to the changes to the of molecular and into the mechanism of by CD48 CD2 molecules the cSMAC (8Grakoui A. Bromley S.K. Sumen C. Davis M.M. Shaw A.S. Allen P.M. Dustin M.L. Science. 1999; 285: 221-227Crossref PubMed Scopus (2512) Google Scholar, R. T. S. S. Curr. Biol. Full Text Full Text PDF PubMed Scopus Google which the of TCR T IS T cells from were on of the different cell that been in the of cells were and for CD2 and Confocal imaging was and were in to of the IS from different of The process to in between in the the to that molecular in the were in the and could not be of the process that when T cells were to cells with CD48-WT, the in of was for CD2 to and T cells to with CD48-CD2 or and than wild CD2 in the of respectively the in of with CD48-CD2 and of with CD48-CD22 was for CD2 to in or more in the of the IS were at not CD2 and CD48 the of TCR and CD2 in large by with the that large as sites in which TCR molecules are and from in were by T cells with the different cell in the of cells were and and the surface was for CD2 and were by as in CD2 and TCR were Both the central and peripheral CD2 were with to TCR We not of CD2 in formed by cells with CD2 were were on the cell and were the contact area. This with the but of CD2 with TCR in T cells A.D. Vale R.D. Cell. 2005; Full Text Full Text PDF PubMed Scopus Google Scholar, M. R. P. S. S. J. Immunol. PubMed Scopus Google Scholar). CD48-WT was in cells, of central CD2 This was a than in the for a TCR cells that also central CD2 from TCR co-localized with CD2 in of the IS with central CD2 In the in which CD2 was in the with TCR was The of CD2 was different for IS with cells CD48-CD2 or CD48-CD22 with a formation of CD2 at of the IS and TCR co-localized with peripheral CD2 in or (CD48-CD22) of synapses this This of TCR with CD2 in the of the IS was in TCR in the cSMAC T cells CD48 forms in and (CD48-CD22) of synapses that of TCR with CD2 in a large in the a TCR was in the were at not TCR with CD2 is the in the when CD48 forms are This is TCR in an where it have interaction with MHCp complexes the of T cell We with planar bilayers and imaging of T IS in to the of adhesion molecule segregation by size and to T cell have that for the CD2 family adhesion the size of the by two or Ig-like adhesion by which was not that of different with each other if the in intermembrane spacing is can segregated adhesion in the contact area. that in the mixed contact small molecules than when the molecules are efficient in mediating that interaction of CD2 with CD48 in a dramatic of the immunological synapse with formation of an with to has been that the of small adhesion molecules like could interactions by the (3Springer T.A. Nature. 1990; 346: 425-434Crossref PubMed Scopus (5816) Google Scholar). it was that four Ig-like to the CD2 ligand an at but was for adhesion at or in a in the of antigen Springer T.A. Biol. Cell. 1992; 3: PubMed Scopus Google Scholar). have used planar in which interactions a contact M.L. D.E. Zhu D.M. J.M. W. Davies E.A. van der Merwe P.A. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). that CD48 by two or the of CD48 to adhesion by 10-fold at We not the not have the to the of forms of CD48 from the contact areas. the for a 10-fold of CD48 forms to adhesion is with a 10-fold The cells of the CD48 forms to the adhesion this in between CD48-WT and forms was tomography are with that Ig-like intermembrane spacing by nm K. K. van der Merwe P.A. Nature. 2005; PubMed Scopus Google Scholar). This that Ig-like are not and in The in intermembrane spacing was between with a contact M.L. D.E. Zhu D.M. J.M. W. Davies E.A. van der Merwe P.A. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). We can that the more CD48 molecules have two with is that the CD2 site of CD48 to a for which the on for the in the is the on The be for more and this of to the of the The interaction an intermembrane distance predicted by of nm (17van der Merwe P.A. McNamee P.N. Davies E.A. Barclay A.N. Davis S.J. Curr. Biol. 1995; 5: 74-84Abstract Full Text Full Text PDF PubMed Scopus (121) Google Scholar, J.H. Smolyar A. Tan K. Liu J.H. Kim M. Sun Z.Y. Wagner G. Reinherz E.L. Cell. 1999; 97: 791-803Abstract Full Text Full Text PDF PubMed Scopus (197) Google Scholar). molecules like CD2 and CD48 also have this in the is that the and interactions an between the of between cells and the and during formation of a contact area. We have used the planar to of for the of the receptor not cytoskeletal but it and it that differential cytoskeletal interactions be a for two by which each other in a contact area. a of the type by and to segregation in IS formation M. C. B. J. Full Text Full Text PDF PubMed Scopus Google Scholar). This adhesion by CD2 to CD48-WT or CD2 to CD48-CD22 interactions as or with that are 10-fold for CD48-WT than for CD48-CD2 or CD48-CD22. areas on the to areas in which CD48-WT or CD48-CD22 to molecules are the for mediating adhesion, can with each other to contacts or as the the of segregated is of mixed contacts in which TCR and LFA-1 microclusters segregate is more to in the of TCR to LFA-1 than the formation of mixed contacts in which CD2 molecules are to of different size (11Varma R. Campi G. Yokosuka T. Saito T. Dustin M.L. Immunity. 2006; 25: 117-127Abstract Full Text Full Text PDF PubMed Scopus (649) Google Scholar). This is related to the in integrin and TCR microclusters Y. Douglass A.D. Varma R. Dustin M.L. Vale R.D. Proc. Natl. Acad. Sci. U. S. A. 2007; 51: 20296-20301Crossref Scopus (285) Google Scholar, 13Campi G. Varma R. Dustin M.L. J. Exp. Med. 2005; 202: 1031-1036Crossref PubMed Scopus (452) Google Scholar, Nat. Cell Biol. 5: PubMed Scopus Google Scholar, S. S.J. K. J.M. Science. PubMed Scopus Google Scholar). into the mechanism by which forms of CD48 T cell antigen A. Davies E.A. H. Saito T. van der Merwe P.A. J. Exp. Med. 1999; PubMed Scopus Google Scholar). We can in the of for T cell signaling in microclusters (11Varma R. Campi G. Yokosuka T. Saito T. Dustin M.L. Immunity. 2006; 25: 117-127Abstract Full Text Full Text PDF PubMed Scopus (649) Google Scholar, 12Kaizuka Y. Douglass A.D. Varma R. Dustin M.L. Vale R.D. Proc. Natl. Acad. Sci. U. S. A. 2007; 51: 20296-20301Crossref Scopus (285) Google Scholar, 13Campi G. Varma R. Dustin M.L. J. Exp. Med. 2005; 202: 1031-1036Crossref PubMed Scopus (452) Google Scholar, 14Yokosuka T. Sakata-Sogawa K. Kobayashi W. Hiroshima M. Hashimoto-Tane A. Tokunaga M. Dustin M.L. Saito T. Nat. Immunol. 2005; 6: 1253-1262Crossref PubMed Scopus (549) Google Scholar). In this model in that are in small or receptors in the that MHCp and microclusters that for and in in the cSMAC that are in a or We propose that CD2 interactions with the CD48 of the TCR in the and from in the signaling The that the CD48 is with A. Davies E.A. H. Saito T. van der Merwe P.A. J. Exp. Med. 1999; PubMed Scopus Google Scholar) and on model for signaling during T cell CD2 with the TCR on the surface of T cells Dustin M. Springer T.A. A. J. Immunol. 1988; Google Scholar, G. M. Nature. PubMed Scopus Google the of CD2 to CD48-CD2 or CD48-CD22 is it the TCR into adhesion that have large an intermembrane for TCR to interact with This can be by the MHCp this the T cell to the of TCR the CD2 that is the CD48 interactions are in a eccentric than the The CD48 interactions be in domains. We have that in the distal supramolecular activation complex lead to lateral that the of the IS and lead to transport of CD2 formed with which into a large (10Sims T.N. Soos T.J. Xenias H.S. Dubin-Thaler B. Hofman J.M. Waite J.C. Cameron T.O. Thomas V.K. Varma R. Wiggins C.H. Sheetz M.P. Littman D.R. Dustin M.L. Cell. 2007; 129: 773-785Abstract Full Text Full Text PDF PubMed Scopus (269) Google Scholar, Dubin-Thaler B. Hofman J. Xenias H.S. T.N. G. Dustin M.L. Wiggins C. Sheetz M.P. Rev. 2006; 97: Scopus Google Scholar). In have that in contacts by the the size of the ligand the intermembrane the adhesion of the and the of the interaction in the contact area. have that pairs segregate from wild type induce in IS and T cell for the first molecular segregation by size and the of this when pairs are We M. R. and G. for and We utilized the of the which is a by the of and with