A novel recognition motif of human NKT antigen receptor for a glycolipid ligand
Tetsu Kawano,
Yujiro Tanaka1,
Eiko Shimizu,
Yoshikatsu Kaneko,
Noriaki Kamata,
Hiroshi Sato,
Hisao Osada2,
Soei Sekiya2,
Toshinori Nakayama and
Masaru Taniguchi
CREST (Core Research for Evolutional Science and Technology) Project and Department of Molecular Immunology,
1 Department of Developmental Immunology, Graduate School of Medicine, and
2 Department of Obstetrics and Gynaecology, School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
Correspondence to:
M Taniguchi
 |
Abstract
|
---|
Murine NKT cells can recognize
-galactosylceramide (
-GalCer) in the context of a class Ib CD1d molecule. Here we show that
-GalCer can selectively activate freshly isolated human V
24+Vß11+ cells, functionally defining the human NKT cells. The naive human NKT cell repertoire consisted of cells expressing an invariant V
24J
Q chain and a diverse array of ß chains derived from a single Vß11 gene segment. Stimulation with
-GalCer expanded a polyclonal subset of the human NKT cell repertoire carrying a novel complementarity-determining region (CDR) 3ß consensus motif that may directly interact with the sugar moiety of
-GalCer. Our data suggest that certain redundancy is allowed for CDR3ß of NKT antigen receptor to interact with the ligand and provide a first clue to understand the novel proteincarbohydrate interaction mechanisms.
Keywords: carbohydrate-binding proteins, complementarity-determining region, NKT antigen receptor, proteinsugar interaction, repertoire selection
 |
Introduction
|
---|
Murine V
14 NKT cells are a unique subset of lymphocytes dedicated for a novel immune antigen, i.e.
-galactosylceramide (
-GalCer) and its analogues, that are presented by class Ib CD1d molecules (1). The NKT antigen receptor consists of an invariant V
14J
281 with a single nucleotide N-region (2,3) and ß chains biased towards Vß8 (3,4). The hemivariant nature of the NKT antigen receptor is consistent with the structure of the CD1d, a half of which antigen binding pocket is closed and thus invariant for the receptor (5). The crystallographic analysis of CD1d also revealed an extremely hydrophobic and narrow antigen-binding groove, implicating that glycolipid ligands bind to CD1d via their hydrophobic lipid tails, whereas hydrophilic sugar moieties are exposed to the solvent. The murine NKT antigen receptor can distinguish stereochemical forms of the sugar, the
-anomeric linkage and the equatorial 2-OH group of the inner sugar playing a crucial role in their recognition and activation (1). The 3,4-hydroxyl groups of the phytosphingosine of
-GalCer are also required for the activation of V
14 NKT cells (1).
Humans have an equivalent of murine V
14 NKT cells, i.e. V
24+Vß11+ NKT cells (3,68). Human V
24 and Vß11 gene segments are the closest homologues of murine V
14 and Vß8 respectively. Notably, the invariant V
J
junction composed of a single nucleotide insertion is conserved between mice and humans (3), suggesting a strict requirement of the canonical
chain for their recognition of target ligands. Since the amino acid sequence homology in the complementarity-determining region (CDR) 3 regions between invariant V
14 and V
24 NKT antigen receptor is >90%, it is conceivable that both murine and human invariant NKT antigen receptor recognize the same or closely related ligands. By contrast, the functional roles of ß chains of NKT antigen receptor remain largely unknown. Here we report that
-GalCer can specifically activate human V
24+Vß11+ cells, functionally defining human NKT cells in fresh samples for the first time. Moreover, we describe a novel consensus motif of the CDR3 of ß-chain (CDR3ß) that was preferentially used by human NKT cells after selection by
-GalCer. Our data provide a structural clue to understand novel proteinsugar interaction mechanisms.
 |
Methods
|
---|
Preparation of V
24 NKT cells
Human umbilical cord blood samples (4050 ml) were collected during labor after obtaining informed consent. The blood was diluted twice with PBS and applied on the half volume of Ficoll-Paque (Amersham Pharmacia Biotech, Uppsala, Sweden). After centrifugation (800 g for 30 min at room temperature), mononuclear cells in the interface were harvested and washed 3 times with PBS. For enrichment of V
24 NKT cells, mononuclear cells were stained with FITC-conjugated anti-V
24 mAb (C15; Coulter-Immunotech, Miami, FL) and then incubated with anti-FITC MACS beads (Miltenyi Biotech, Bergisch Gladbach, Germany) according to the manufacturer's protocol. Cells were then applied to MACS columns (Miltenyi Biotech) and trapped cells were used as V
24 NKT cells for further experiments. In some experiments, V
24+ cells were re-stained with phycoerythrin (PE)-conjugated anti-Vß11 mAb (C21; Coulter-Immunotech) and fractionated into V
24+Vß11+ and V
24+Vß11 cells by an EPICS flow cytometer (Coulter).
Flow cytometry
Cells were three-colour stained with Cychrome-conjugated anti-CD3
mAb (UCHT1; Pharmingen, San Diego, CA) together with anti-V
24 (C15; Coulter-Immunotech) and anti-Vß11 (C21; Coulter-Immunotech) mAb conjugated with either FITC or PE. Samples were analyzed on EPICS-XL (Coulter) with a logarithmic amplifier. Listmode data were analyzed on FlowJo software (Stanford University).
Glycolipids
Synthetic glycolipids were described before (1) and were kindly provided by Pharmaceutical Research Laboratory, Kirin Brewery (Japan). The following synthetic glycolipids were used;
-galactosylceramide (KRN7000): (2S,3S,4R)-1-O-(
-D-galactopyranosyl)-N-hexacosanoyl-2-amino-1,3,4-octa-decanetriol; ß-galactosylceramide: (2S,3S,4R)-1-O-(ß-D-galactopyranosyl)-N-hexacosanoyl-2-amino-1,3,4-octadecane-triol;
-glucosylceramide: (2S,3S,4R)-1-O-(
-D-glucopyranosyl)-N-hexacosanoyl-2-amino-1,3,4-octadecanetriol;
-mannosylceramide: (2S,3S,4R)-2-amino-N-hexacosanoyl-1-O-(
-D-mannopyranosyl)-1,3,4-octadecanetriol-3,4-deoxy
-galactosylceramide: (2S)-1-O-(
-D-galactopyranosyl)-N-tetracosanoyl-2-amino-1-octadecanol, ceramide: (2S,3S,4R)-N-hexacosanoyl-2-amino-1,3,4-octadecanetriol. All reagents were stored in 100% DMSO at 100 µg/ml at 20°C. For in vitro assay, reagents were first diluted in PBS and then added to final cultures. DMSO treated in the same way as glycolipids was used as a negative control (vehicle).
Proliferation assay
The autologous antigen-presenting cells (APC) were prepared from human umbilical cord blood by depleting CD3+ cells using MACS columns. The lack of contamination was checked by an EPICS. Subsequently, V
24 NKT cells (7x104 cells/well) were co-cultured with APC (6x105 cells/well) in 96-well round-bottom tissue culture plates (Falcon) in the complete media, i.e. RPMI-1640 supplemented with 10% heatinactivated FCS (Sanko Jyunyaku, Tokyo, Japan), 2 mM L-glutamate and penicillin/streptomycin (tissue culture reagents were purchased from Life Technologies unless otherwise mentioned), in the presence or absence of synthetic glycolipids. Proliferative responses of V
24 NKT cells were evaluated by [3H]thymidine incorporation. Briefly, 1 µCi of [3H]thymidine (Amersham Pharmacia Biotech) was added in each well during the last 12 h in a total of 72 h of culture and the uptake was measured by a liquid scintillation counter. In some experiments, V
24+ cells and V
24 cells (1x105 cells/well) were cultured (without additional APC) in the presence of
-GalCer for 72 h in 96-well round-bottom plates.
Long-term culture of V
24 NKT cells
Purified V
24+Vß11+ cells or V
24+Vß11 cells (3.7x103 cells/well) were co-cultured with autologous APC (1x106 cells/well) in the complete medium in the presence of
-GalCer at the concentration of 10 ng/ml, with 100 U/ml recombinant human IL-2 (Boehringer Mannheim, Mannheim, Germany). Culture media were replaced every 23 days with fresh ones together with glycolipids and IL-2, and maintained up to 4 weeks. In some experiments, unfractionated cord blood mononuclear cells (1x106 cells/well) were cultured in the presence of 1, 10 or 100 ng/ml
-GalCer with or without 100 U/ml IL-2.
Sequencing of NKT and TCR
and ß chains
Total mRNA was isolated using TRIzol and first-strand cDNA was synthesized with 200 U SuperScript, RNaseH-free reverse transcriptase (all purchased from Life Technologies) and oligo-dT primers. Nested PCR was performed using 1xPCR buffer containing 1.5 mM MgCl2, 200 µM each of dNTP, 1 µM primers and 2.5 U AmpliTaq DNA polymerase (Perkin Elmer, Norwalk, CT) according to the manufacturer's protocol using a PTC-200 Peltier Thermal Cycler (MJ Research, Massachussetts, MA). Samples were heated to 94°C for 3 min, and then subjected to 30 cycles of amplification by 15 s at 94°C, 30 s at 52°C and 1 min at 72°C with 3 s extension per each cycle. Oligonucleotide primers used were as follows: V
24 outer primer: 5'-GGGAGCAGATCTCTGCAG-3'; V
24 inner primer, 5'-CCCGAGCTCATGAAAAAGCATCTGACG-3'; C
primer, 5'-GCCCGGCCGGGTCAGGGTTCTGGATATCAGGCCAGAC-3'; Vß11 outer primer, 5'-TACTGGGAGACATCCTCT-3'; Vß11 inner primer, 5'-GCTCTAGATCATGACTATCAGGCTCCTC-3'; Cß outer primer, 5'-TCTAGAATTCTTCTGATGGCTCAAACAC-3'; and Cß inner primer, 5'-CCTCGGGTGGGAACAC-3'.
After gel electrophoresis, specific PCR products were excised out and DNA was extracted using a QIAEX II gel extraction kit (QIAGEN, Hilden, Germany) and cloned into pGEM-T vector (Promega, Madison, WI). Nucleotide sequences of each clone were determined by the PCR sequencing method using AmpliTaq DNA polymerase, BigDye primer cycle sequencing kit (PE Applied Biosystems, Foster, CA) and an ABI Prism 310 sequencer (PE Applied Biosystems) according to the manufacturer's protocol.
 |
Results
|
---|
-GalCer can activate freshly isolated human V
24+ cells
Human V
24+Vß11+ cells are thought to be an equivalent of murine V
14 NKT cells (3,69). Human umbilical cord blood and adult peripheral blood contain comparable proportions of V
24+Vß11+ cells, i.e. 0.061 ± 0.026% (0.0200.121%, n = 17) and 0.059 ± 0.063% (0.0010.200%, n = 9) of mononuclear cells respectively. In addition, bulk culture experiments suggested that human umbilical cord blood contains cells that can be activated by
-GalCer (data not shown). To confirm if these are indeed human NKT cells, V
24+ cells were enriched to 3.5% and their responses to either
-GalCer or control vehicle were compared to those of cord blood cells depleted of V
24+ cells. As shown in Fig. 1
(A), V
24+ but not V
24 cells proliferated in response to
-GalCer. Moreover, human V
24+ cells recognized the same range of glycolipid analogues as murine V
14 NKT cells as shown in Fig. 1
(B), suggesting that they share highly homologous receptor structures.
-GalCer selectively expands V
24+Vß11+ cells
To further verify which population of cells are responding to
-GalCer, V
24+Vß11+ and V
24+Vß11 cells were purified from human umbilical cord blood and 3.7x103 of each were co-cultured for 2 weeks with 1x106 autologous APC depleted of CD3+ cells (responder to APC ratio; 3.7:1000) in the presence of
-GalCer (10 ng/ml) and 100 U/ml IL-2. As shown in Fig. 2
(A), no V
24+ or Vß11+ T cells appeared in culture of APC only. Culture of V
24+Vß11+ cells resulted in their expansion in both proportion and absolute number. By contrast, there was no increase in cell number in the culture of V
24+Vß11 cells. Similar experiments were repeated using adult peripheral blood or umbilical cord blood cells partially enriched (0.16%) for V
24+Vß11+ cells and yielded 6392% of V
24+Vß11+ cells after stimulation with
-GalCer for 2 weeks (data not shown).
In the second set of experiments, unfractionated mononuclear leukocytes were cultured in the presence of different amounts of
-GalCer with or without IL-2. As shown in Fig. 2
(B), fold-increase in absolute number of V
24+Vß11+ cells reached 220 times at maximum when 10 ng/ml
-GalCer and 100 U/ml IL-2 were present in culture. By contrast, the number of V
24+Vß11 cells did not increase even with the highest concentration of
-GalCer. Taken together, these data establish that V
24+Vß11+ cells are selectively expanded in cultures with
-GalCer, functionally defining human NKT cells in fresh samples.
Pre-selected human NKT cell repertoire is highly polyclonal
To elucidate the structural basis for the ligand recognition by human NKT cells, TCR sequences were determined for both NKT and non-NKT cells. To this end, V
24+Vß11+ NKT and V
24Vß11+ T cells were freshly isolated from mononuclear leukocytes, and their mRNA was reverse transcribed and amplified by PCR using primer sets specific for V
24C
and Vß11Cß. PCR products were cloned into a pGEM-T vector and sequenced from vector primers. As reported before (8), the
chain of V
24+Vß11+ NKT cells always used the J
Q gene segment and their VJ junctions were invariant (data not shown). By contrast, the ß chains of V
24+Vß11+ NKT cells were highly heterogeneous in length and amino acid composition in CDR3 loops (Fig. 3A
). However, in comparison to CDR3 sequences of V
24Vß11+ T cells (conventional T cells, Fig. 3A
), those of V
24+Vß11+ NKT cells preferentially used serine at position 95 followed by either charged or small amino acids (aspartate, glutamate, glycine and alanine) at position 96. The coding sequence for serine 95 is derived from the germline Vß11, whereas that of the residue at position 96 is composed from VDJ junction, strongly suggesting an in vivo selection of the human NKT repertoire by endogenous ligands.
-GalCer selects a subset of human NKT cell repertoire
To test if
-GalCer is recognized by a specific structure of NKT antigen receptor, mononuclear leukocytes were cultured as in Fig. 2
(A) and the expanded V
24+Vß11+ NKT cells were purified by cell sorting. The absolute number of V
24+Vß11+ NKT cells increased by 56 and 320 times for case 1 and 2 respectively, suggesting that non-selected clones were diluted below a few percents. Transcripts from the ligand-selected V
24+Vß11+ NKT cells were reverse transcribed and PCR amplified using primers for Vß11 and Cß. PCR products were cloned and sequenced as above. As summarized in Fig. 3
(B), it is evident that human NKT cells responding to
-GalCer are highly polyclonal and carry CDR3ß loops of different size and composition. Nevertheless, the repertoire size was significantly reduced because those CDR3ß sequences which were observed multiple times were encoded by identical DNA sequences. In addition, the expanded clones differed from case to case, suggesting that
-GalCer selected specific clones that pre-existed in the individual's naive repertoire. Despite such a heterogeneity, most clones fit with a novel CDR3ß consensus motif as illustrated in Fig. 4
. The consensus CDR3ß loop begins with serine at position 95, followed by acidic residues (aspartate and glutamate) or arginine or both, then by hydrophobic residues (mostly glycine, leucine and valine) and ends with another hydrophilic residues (threonine, aspartate and glutamate). The same motif already predominates the pre-selection human NKT repertoire compared to conventional T cells and is further enriched after selection by
-GalCer as confirmed by statistical analysis (Fig. 5
).
 |
Discussion
|
---|
The naive human NKT repertoire expresses an invariant V
24J
Q and heterogeneous ß chains derived from Vß11. Here we demonstrated that
-GalCer can polyclonally stimulate a subset of the human NKT repertoire. The selected NKT cells carried CDR3ß of various length but preferentially used a novel consensus motif consisting of serine and a combination of hydrophilichydrophobichydrophilic residues (Fig. 4
), which were under-represented in conventional T cells. Those conventional T cells which do possess the consensus CDR3ß sequence cannot expand in response to
-GalCer (Fig. 2B
) because they lack the canonical V
24J
Q chain. The consensus motif was selected reproducibly in two independent experiments despite the fact that actual sequences were different. Moreover, the same consensus motif is expressed also by non-stimulated murine V
14 NKT cells (4). Intriguingly, CDR3
of the canonical V
24J
Q chain falls in the same motif, implying a possible evolutionary history of an archaic homodimeric NKT antigen receptor. Despite such a rule, there was no strict requirement for a specific residue at any given position except for the first serine.
Is the redundancy a general feature of TCRligand interaction? In previous studies using TCR
transgenic mice, peptide antigens have been shown to select T cells with heterogeneous Vß gene segments and diverse VDJ junctions (1012). Such studies were, however, complicated by the expression of endogenous TCR
chains because there is no allelic exclusion in the TCR
locus. More recently, TCR
transgenic mice in a TCR
/ background were used to avoid the expression of endogenous TCR
chains (13). Immunization of these mice with peptide antigens selected a subset of T cells which carried TCRß chains derived from a single Vß. Moreover, the length of the CDR3ß loop was fixed and the same residue was always used at a specific position. Thus, there is little redundancy in TCRligand interactions if half of the receptor (TCR
chain) is fixed, in contrast to variations in length and amino acid composition of NKT antigen receptor CDR3ß.
How could, then, different CDR3ß structures be tolerated while all other CDR loops, antigen and CD1d molecules are fixed? From the crystallographic studies of human TCRMHCpeptide complexes (14) and murine CD1d (5), NKT antigen receptor are expected to approach the CD1d molecule by a diagonal orientation similar to TCRMHC interactions, avoiding protrusions of N-termini of CD1d
-helices. If the invariant
chain of NKT antigen receptor interacts with the closed surface of the CD1d A' pocket, the CDR3ß loop is placed over the F' pocket. Charged residues are concentrated around the orifice of F' pocket, in contrast to the highly hydrophobic environment of the antigen-binding groove (5), suggesting that the carbohydrate moiety of
-GalCer is exposed to the solvent near F' pocket and therefore interacts with the ß chain CDR loops of NKT antigen receptor. Such a model is compatible with recently published computer models of
-GalCer and
-GlcCer (two of the agonistic ligands) that can be superposed with each other (15).
In proteinsugar interactions, qualitative differences have been noted between Ig and other carbohydrate-binding proteins. Carbohydrate ligands in complexes with Fab fragments are held by hydrogen bonds and van der Waals' contacts to aromatic side chains or to main chain atoms of CDR loops in the two co-crystals of Fabcarbohydrate complexes solved to date (16,17). Notably, all four residues (16) or four out of six residues (17) in heavy chain CDR3 loops were aromatic and contacted antigens largely through main chain atoms. By contrast, other proteincarbohydrate interactions are characterized by hydrogen-bonding networks of negatively charged (aspartate and glutamate) and amide (asparagine and glutamine) side chains with hydroxyl groups of sugars, as well as stacking of aromatic side chains with hexose rings of carbohydrates (18). The unique combination of hydrophilic and hydrophobic residues and the lack of strict requirement of specific residues in NKT antigen receptor may suggest that the hydrophobic residues in the middle interact with ligands through main chain atoms similar to Igcarbohydrate interactions. Promiscuous recognition has also been observed in the interaction between TCRß and superantigen (19) as well as in that between peptide and MHC (20), where backbone atoms but not side chain atoms were involved in hydrogen bonds. Such `conformation-dependent, but sequence-independent' recognition mechanisms may be revealed only by structural studies.
Both murine and human NKT cells distinguish galactose from mannose in
-GalCer, reminiscent of a general classification of C-type lectins into mannose or galactose types (21). Thus, C-type lectins recognize either vicinal, equatorial 3,4-OH groups of mannose or the equatorial 4-OH group of galactose, which form co-ordination bonds with Ca2+ and hydrogen bonds with carbohydrate-recognition domain (CRD) residues of lectins in crystals (21). By contrast, NKT antigen receptor can recognize C1-
-linkage (axial) and equatorial 2-OH of galactose and glucose but neither axial 2-OH of mannose or C1-ß-linkage (equatorial), suggesting that these two receptorligand interactions are mediated by distinct mechanisms. Accordingly, there is no amino acid sequence homology between the CDR3ß of NKT antigen receptor and the CRD of C-type lectins.
In the current study, we have shown that human umbilical cord blood is a relatively rich source of NKT cells. Although the function of human NKT cells in vivo remains to be established, the availability of a specific ligand for human NKT cells opens a new way to clinical interventions not only for killing residual malignant cells after cord blood transplantation into childhood, but also for treatments of adult cancer (22), autoimmune diseases (23) and mycobacterial infections (T. Kawano. unpublished). In this context, we have already confirmed that human NKT cells activated by
-GalCer can kill a panel of human cancer cell lines in vitro (T. Kawano et al., manuscript in preparation). Knowledge of molecular mechanisms of NKT antigen receptorligand interactions will help develop further reagents to manipulate human NKT cells in vivo.
 |
Acknowledgments
|
---|
We thank Kirin Brewery Co. Ltd for providing us with glycolipid reagents, Ms Kazuko Higashino for technical assistance and Ms Hiroko Tanabe for secretarial work. This work was supported in part by a Grant-in-Aid for Scientific Research on Priority Areas (06282103) from the Ministry of Education, Culture, Sports and Science, Japan, and by a grant from Taisho Pharmaceutical Company Co. Ltd, Japan.
 |
Abbreviations
|
---|
-GalCer | -galactosylceramide |
APC | antigen-presenting cell |
CDR3 | complementarity-determining region 3 |
CRD | carbohydrate-recognition domain |
PE | phycoerythrin |
 |
Notes
|
---|
Transmitting editor: T. Watanabe
Received 1 December 1998,
accepted 12 February 1999.
 |
References
|
---|
-
Kawano, T., Cui, J., Koezuka, Y., Toura, I., Kaneko, Y., Motoki, K., Ueno, H., Nakagawa, R., Sato, H., Kondo, E., Koseki, H. and Taniguchi, M. 1997. CD1d-restricted and TCR-mediated activation of V
14 NKT cells by glycosylceramides. Science 278:1626.[Abstract/Free Full Text]
-
Imai, K., Kanno, M., Kimoto, H., Shigemoto, K., Yamamoto, S. and Taniguchi, M. 1986. Sequence and expression of transcripts of the T-cell antigen receptor
-chain gene in a functional, antigen-specific suppressor-T-cell hybridoma. Proc. Natl Acad. Sci. USA 83:8708.[Abstract]
-
Lantz, O. and Bendelac, A. 1994. An invariant T cell receptor a chain is used by a unique subset of major histocompatibility complex class I-specific CD4+ and CD48 T cells in mice and humans. J. Exp. Med. 180:1097.[Abstract]
-
Masuda, K., Makino, Y., Cui, J., Ito, T., Tokuhisa, T., Takahama, Y., Koseki, H., Tsuchida, K., Koike, T., Moriya, H., Amano, M. and Taniguchi, M. 1997. Phenotypes and invariant
ß TCR expression of peripheral V
14+ NK T cells. J. Immunol. 158:2076.[Abstract]
-
Zeng, Z.-H., Castano, A. R., Segelke, B. W., Stura, E. A., Peterson, P. A. and Wilson, I. A. 1997. Crystal structure of mouse CD1: an MHC-like fold with a large hydrophobic binding groove. Science 277:339.[Abstract/Free Full Text]
-
Davodeau, F., Peyrat, M.-A., Necker, A., Dominici, R., Blanchard, F., Leget, C., Gaschet, J., Costa, P., Jacques, Y., Godard, A., Vié, H., Poggi, A., Romagné, F. and Bonneville, M. 1997. Close phenotypic and functional similarities between human and murine
ß T cells expressing invariant TCR
-chains. J. Immunol. 158:5603.[Abstract]
-
Exley, M., Garcia, J., Balk, S. P. and Porcelli, S. 1997. Requirements for CD1d recognition by human invariant V
24+ CD4CD8 T cells. J. Exp. Med. 186:109.[Abstract/Free Full Text]
-
Prussin, C. and Foster, B. 1997. TCR V
24 and Vß11 coexpression defines a human NK1 T cell analog containing a unique Th0 subpopulation. J. Immunol. 159:5862.[Abstract]
-
Porcelli, S., Yockey, C. E., Brenner, M. B. and Balk, S. P. 1993. Analysis of T cell antigen receptor (TCR) expression by human peripheral blood CD48
/ß T cells demonstrates preferential use of several Vß genes and an invariant TCR
chain. J. Exp. Med. 178:1.[Abstract]
-
Jorgensen, J. L., Esser, U., Fazekas de St. Groth, B., Reay, P. A. and Davis, M. M. 1992. Mapping T-cell receptorpeptide contacts by variant peptide immunization of single-chain transgenics. Nature 355:224.[ISI][Medline]
-
Kelly, J. M., Sterry, S. J., Cose, S., Turner, S. J., Fecondo, J., Rodda, S., Fink, P. J. and Carbone, F. R. 1993. Identification of conserved T cell receptor CDR3 residues contacting known exposed peptide side chains from a major histocompatibility complex class I-bound determinant. Eur. J. Immunol. 23:3318.[ISI][Medline]
-
Sant'Angelo, D. B., Waterbury, G., Preston-Hurlburt, P., Yoon, S. T., Medzhitov, R., Hong, S.-c. and Janeway, C. A., Jr 1996. The specificity and orientation of a TCR to its peptideMHC class II ligands. Immunity 4:367.[ISI][Medline]
-
Wang, F., Ono, T., Kalergis, A. M., Zhang, W., DiLorenzo, T. P., Lim, K. and Nathenson, S. G. 1998. On defining the rules for interactions between the T cell receptor and its ligand: a critical role for a specific amino acid residue of the T cell receptor ß chain. Proc. Natl Acad. Sci. USA 95:5217.[Abstract/Free Full Text]
-
Garboczi, D. N., Ghosh, P., Utz, U., Fan, Q. R., Biddison, W. E. and Wiley, D. C. 1996. Structure of the complex between human T-cell receptor, viral peptide and HLA-A2. Nature 384:134.[ISI][Medline]
-
Iijima, H., Kimura, K., Sakai, T., Uchimura, A., Shimizu, T., Ueno, H., Natori, T. and Koezuka, Y. 1998. Structureactivity relationship and conformational analysis of monoglycosylceramides on the syngeneic mixed leukocyte reaction. Bioorg. Med. Chem. 6:1905.[ISI][Medline]
-
Cygler, M., Rose, D. R. and Bundle, D. R. 1991. Recognition of a cell-surface oligosaccharide of pathogenic Salmonella by an antibody Fab fragment. Science 253:442.[ISI][Medline]
-
Jeffrey, P. D., Bajorath, J., Chang, C. Y., Yelton, D., Hellström, I., Hellström, K. E. and Sheriff, S. 1995. The X-ray structure of an anti-tumour antibody in complex with antigen. Nat. Struct. Biol. 2:466.[ISI][Medline]
-
Quiocho, F. A. 1986. Carbohydrate-binding proteins: tertiary structures and proteinsugar interactions. Annu. Rev. Biochem. 55:287.[ISI][Medline]
-
Fields, B. A., Malchiodi, E. L., Li, H., Ysern, X., Stauffacher, C. V., Schlievert, P. M., Karjalainen, K. and Mariuzza, R. A. 1996. Crystal structure of a T-cell receptor ß-chain complexed with a superantigen. Nature 384:188.[ISI][Medline]
-
Fremont, D. H., Matsumura, M., Stura, E. A., Peterson, P. A. and Wilson, I. A. 1992. Crystal structures of two viral peptides in complex with murine MHC class I H-2Kb. Science 257:919.[ISI][Medline]
-
Weis, W. I., Taylor, M. E. and Drickamer, K. 1998. The C-type lectin superfamily in the immune system. Immunol. Rev. 163:19.[ISI][Medline]
-
Cui, J., Shin, T., Kawano, T., Sato, H., Kondo, E., Toura, I., Kaneko, Y., Koseki, H., Kanno, M. and Taniguchi, M. 1997. Requirement for V
14 NK T cells in IL-12-mediated rejection of tumors. Science 278:1623.[Abstract/Free Full Text]
-
Sumida, T., Sakamoto, A., Murata, H., Makino, Y., Takahashi, H., Yoshida, S., Nishioka, K., Iwamoto, I. and Taniguchi, M. 1995. Selective reduction of T cells bearing invariant V
24J
Q antigen receptor in patients with systemic sclerosis. J. Exp. Med. 182:1163.[Abstract]