The structure of the rat vitamin B12 transporter TC and its complex with glutathionylcobalamin.

Vitamin B12 (cobalamin or Cbl) functions as a cofactor in two important enzymatic processes in human cells, and life is not sustainable without it. B12 is obtained from food and travels from the stomach, through the intestine, and into the bloodstream by three B12-transporting proteins: salivary haptocorrin (HC), gastric intrinsic factor, and transcobalamin (TC), which all bind B12 with high affinity and require proteolytic degradation to liberate Cbl. After intracellular delivery of dietary B12, Cbl in the aquo/hydroxocobalamin form can coordinate various nucleophiles, for example, GSH, giving rise to glutathionylcobalamin (GSCbl), a naturally occurring form of vitamin B12. Currently, there is no data showing whether GSCbl is recognized and transported in the human body. Our crystallographic data shows for the first time the complex between a vitamin B12 transporter and GSCbl, which compared to aquo/hydroxocobalamin, binds TC equally well. Furthermore, sequence analysis and structural comparisons show that TC recognizes and transports GSCbl and that the residues involved are conserved among TCs from different organisms. Interestingly, haptocorrin and intrinsic factor are not structurally tailored to bind GSCbl. This study provides new insights into the interactions between TC and Cbl.

Single crystal spectroscopy and multiple structures from one crystal (MSOX) define catalysis in copper nitrite reductases.

Many enzymes utilize redox-coupled centers for performing catalysis where these centers are used to control and regulate the transfer of electrons required for catalysis, whose untimely delivery can lead to a state incapable of binding the substrate, i.e., a dead-end enzyme. Copper nitrite reductases (CuNiRs), which catalyze the reduction of nitrite to nitric oxide (NO), have proven to be a good model system for studying these complex processes including proton-coupled electron transfer (ET) and their orchestration for substrate binding/utilization. Recently, a two-domain CuNiR from a Rhizobia species (Br2DNiR) has been discovered with a substantially lower enzymatic activity where the catalytic type-2 Cu (T2Cu) site is occupied by two water molecules requiring their displacement for the substrate nitrite to bind. Single crystal spectroscopy combined with MSOX (multiple structures from one crystal) for both the as-isolated and nitrite-soaked crystals clearly demonstrate that inter-Cu ET within the coupled T1Cu-T2Cu redox system is heavily gated. Laser-flash photolysis and optical spectroscopy showed rapid ET from photoexcited NADH to the T1Cu center but little or no inter-Cu ET in the absence of nitrite. Furthermore, incomplete reoxidation of the T1Cu site (∼20% electrons transferred) was observed in the presence of nitrite, consistent with a slow formation of NO species in the serial structures of the MSOX movie obtained from the nitrite-soaked crystal, which is likely to be responsible for the lower activity of this CuNiR. Our approach is of direct relevance for studying redox reactions in a wide range of biological systems including metalloproteins that make up at least 30% of all proteins.

Structural and Functional Analyses of Inhibition of Human Dihydroorotate Dehydrogenase by Antiviral Furocoumavirin.

Natural products are important sources of seed compounds for drug discovery. However, it has become difficult in recent years to discover new compounds with valuable pharmacological activities. On the other hand, among the vast number of natural products that have been isolated so far, a considerable number of compounds with specific biological activities are thought to be overlooked in screening that uses biological activity as an index. Therefore, it is conceivable that such overlooked useful compounds may be found by screening compound libraries that have been amassed previously through specific assays. Previously, NPD723, a member of the Natural Products Depository library comprised of a mixture of natural and non-natural products developed at RIKEN, and its metabolite H-006 were found to inhibit growth of various cancer cells at low nanomolar half-maximal inhibitory concentration. Subsequent analysis revealed that H-006 strongly inhibited human dihydroorotate dehydrogenase (DHODH), the rate-limiting enzyme in the de novo pyrimidine biosynthetic pathway. Here, we elucidated the crystal structure of the DHODH-flavin mononucleotide-orotic acid-H-006 complex at 1.7 Å resolution to determine that furocoumavirin, the S-enantiomer of H-006, was the actual inhibitor. The overall mode of interaction of furocoumavirin with the inhibitor binding pocket was similar to that described for previously reported tight-binding inhibitors. However, the structural information together with kinetic characterizations of site-specific mutants identified key unique features that are considered to contribute to the sub-nanomolar inhibition of DHODH by furocoumavirin. Our finding identified new chemical features that could improve the design of human DHODH inhibitors.

Long term results with the interlocking uncemented long stem in revision hip arthroplasty: a mean 15-year follow-up.

Stem fixation is difficult to achieve in severe proximal bone loss in revision hip surgery. In this study, we sought to present the results of distally-locked stem with screws (HUCKESTEP HIP stem) in 21 revision hips with mean follow-up period of 15 years. The preoperative mean Japanese Orthopaedic Association hip score had improved from 54 to 75 points. Further revisions were required for 2 stems, in one because of infection and the other because of screws fracture and subsidence. With removal of the stem for any reason as an end-point, the cumulative survival at 15 years was 90.4%. While this study had small number, the use of this interlocking stem for revision hips with extensive proximal bone defects provided satisfactory 15-year clinical and radiographic results.

SPring-8 BL41XU, a high-flux macromolecular crystallography beamline.

SPring-8 BL41XU is a high-flux macromolecular crystallography beamline using an in-vacuum undulator as a light source. The X-rays are monochromated by a liquid-nitrogen-cooling Si double-crystal monochromator, and focused by Kirkpatrick-Baez mirror optics. The focused beam size at the sample is 80 µm (H) × 22 µm (V) with a photon flux of 1.1 × 10(13) photons s(-1). A pinhole aperture is used to collimate the beam in the range 10-50 µm. This high-flux beam with variable size provides opportunities not only for micro-crystallography but also for data collection effectively making use of crystal volume. The beamline also provides high-energy X-rays covering 20.6-35.4 keV which allows ultra-high-resolution data to be obtained and anomalous diffraction using the K-edge of Xe and I. Upgrade of BL41XU for more rapid and accurate data collection is proceeding. Here, details of BL41XU are given and an outline of the upgrade project is documented.

Minimally invasive surgery using intraoperative real-time capsule endoscopy for small bowel lesions.

BACKGROUND: The small bowel has been considered the "black box" of gastroenterology. Identifying the exact site of small bowel hemorrhage is often difficult, thus complicating surgical treatment. We report two cases of small bowel bleeding lesions that were successfully managed by intraoperative real-time capsule endoscopy and minimally invasive surgery. METHODS: We developed a double-lumen tube similar to, but thinner and longer than, the Miller-Abbott tube. We insert the tube nasally, 3 or 4 days preoperatively, such that its balloon tip reaches the anus by the operative day. During surgery, the endoscopic capsule is connected to the balloon tip of the tube that protrudes from the anus. An assistant pulls on the nasal end of the tube, bringing the balloon tip and capsule back into the bowel. Capsule endoscopic images are displayed in a real-time video format. RESULTS: We employed this procedure in two patients with repeated melena. Various examinations including gastroendoscopy and total colonoscopy showed bleeding confined to the small bowel, but the exact lesion site was unknown. Minimally invasive surgery was successfully performed in both patients: open minilaparotomy in one and laparoscopy in the other. The small bowel and capsule endoscope were easily controlled during minilaparotomy, and real-time capsule endoscopic images clearly identified the bleeding lesion. Control of the small bowel was more difficult in the laparoscopic case; however, real-time capsule endoscopic images identified a small tumor that was successfully resected. CONCLUSIONS: Intraoperative capsule endoscopy combined with the tube provides surgeons real-time images indicating the exact site of lesions. The tube also helps surgeons control the position of the capsule endoscope and enables suction of intraluminal fluid or inflation of the lumen to allow clearer views during the operation. We conclude that combined use of capsule endoscopy and the tube facilitates management of bleeding lesions in the small bowel.

A point mutation in ftmD blocks the fumitremorgin biosynthetic pathway in Aspergillus fumigatus strain Af293.

Fumitremorgins (FTMs), tremorgenic mycotoxins produced by the human pathogen Aspergillus fumigatus, are prenylated indole alkaloids that have been extensively studied in view of their diverse chemical structures and biological activities. Their biosynthetic gene (ftm) cluster was identified on the basis of the genome sequence of A. fumigatus. However, it has been reported that the ftm cluster in genome reference strain Af293 is inactive, which makes complete understanding of the FTM pathway difficult. Hence, we used an FTM-producing strain of A. fumigatus, BM939, to dissect the FTM pathway. Here, we delineate the genetic determinant for the observed defect in the FTM pathway in A. fumigatus Af293. Metabolite profiling and sequence comparison of the two strains revealed a point mutation in ftmD as a possible cause of altered metabolite production in strain Af293. FTM production in Af293 was restored when a DNA fragment containing ftmD from BM939 was introduced. Biochemical analysis indicated that FtmD is a methyltransferase that catalyzes the conversion of 6-hydroxytryprostatin B into tryprostatin A. The mutated FtmD retained enzymatic activity but did not function under physiological conditions, resulting in blockage of the FTM pathway in A. fumigatus Af293.

A small-molecule inhibitor shows that pirin regulates migration of melanoma cells.

The discovery of small molecules that bind to a specific target and disrupt the function of proteins is an important step in chemical biology, especially for poorly characterized proteins. Human pirin is a nuclear protein of unknown function that is widely expressed in punctate subnuclear structures in human tissues. Here, we report the discovery of a small molecule that binds to pirin. We determined how the small molecule bound to pirin by solving the cocrystal structure. Either knockdown of pirin or treatment with the small molecule inhibited melanoma cell migration. Thus, inhibition of pirin by the small molecule has led to a greater understanding of the function of pirin and represents a new method of studying pirin-mediated signaling pathways.

Structures of oxygen dissociation intermediates of 400 kDa V2 hemoglobin provide coarse snapshots of the protein allostery.

Ever since the historic discovery of the cooperative oxygenation of its multiple subunits, hemoglobin (Hb) has been among the most exhaustively studied allosteric proteins. However, the lack of structural information on the intermediates between oxygenated and deoxygenated forms prevents our detailed understanding of the molecular mechanism of its allostery. It has been difficult to prepare crystals of intact oxy-deoxy intermediates and to individually identify the oxygen saturation for each subunit. However, our recent crystallographic studies have demonstrated that giant Hbs from annelids are suitable for overcoming these problems and can provide abundant information on oxy-deoxy intermediate structures. Here, we report the crystal structures of oxy-deoxy intermediates of a 400 kDa Hb (V2Hb) from the annelid Lamellibrachia satsuma, following up on a series of previous studies of similar giant Hbs. Four intermediate structures had average oxygen saturations of 78%, 69%, 55%, and 26%, as determined by the occupancy refinement of the bound oxygen based on ambient temperature factors. The structures demonstrate that the cooperative oxygen dissociation is weaker, large ternary and quaternary changes are induced at a later stage of the oxygen dissociation process, and the ternary and quaternary changes are smaller with local perturbations. Nonetheless, the overall structural transition seemed to proceed in the manner of the MWC two-state model. Our crystallographic snapshots of the allosteric transition of V2Hb provide important experimental evidence for a more detailed understanding of the allostery of Hbs by extension of the Monod-Wyman-Changeux (MWC) model.

In situ crystal data-collection and ligand-screening system at SPring-8.

In situ diffraction data collection using crystallization plates has been utilized for macromolecules to evaluate crystal quality without requiring additional sample treatment such as cryocooling. Although it is difficult to collect complete data sets using this technique due to the mechanical limitation of crystal rotation, recent advances in methods for data collection from multiple crystals have overcome this issue. At SPring-8, an in situ diffraction measurement system was constructed consisting of a goniometer for a plate, an articulated robot and plate storage. Using this system, complete data sets were obtained utilizing the small-wedge measurement method. Combining this system with an acoustic liquid handler to prepare protein-ligand complex crystals by applying fragment compounds to trypsin crystals for in situ soaking, binding was confirmed for seven out of eight compounds. These results show that the system functioned properly to collect complete data for structural analysis and to expand the capability for ligand screening in combination with a liquid dispenser.

The identification of an osteoclastogenesis inhibitor through the inhibition of glyoxalase I.

Osteoclasts, bone-resorptive multinucleated cells derived from hematopoietic stem cells, are associated with many bone-related diseases, such as osteoporosis. Osteoclast-targeting small-molecule inhibitors are valuable tools for studying osteoclast biology and for developing antiresorptive agents. Here, we have discovered that methyl-gerfelin (M-GFN), the methyl ester of the natural product gerfelin, suppresses osteoclastogenesis. By using M-GFN-immobilized beads, glyoxalase I (GLO1) was identified as an M-GFN-binding protein. GLO1 knockdown and treatment with an established GLO1 inhibitor in osteoclast progenitor cells interfered with osteoclast generation, suggesting that GLO1 activity is required for osteoclastogenesis. In cells, GLO1 plays a critical role in the detoxification of 2-oxoaldehydes, such as methylglyoxal. M-GFN inhibited the enzymatic activity of GLO1 in vitro and in situ. Furthermore, the cocrystal structure of the GLO1/M-GFN complex revealed the binding mode of M-GFN at the active site of GLO1. These results suggest that M-GFN targets GLO1, resulting in the inhibition of osteoclastogenesis.

Coarse snapshots of oxygen-dissociation intermediates of a giant hemoglobin elucidated by determining the oxygen saturation in individual subunits in the crystalline state.

Cooperative oxygen binding of hemoglobin (Hb) has been studied for over half a century as a representative example of the allostericity of proteins. The most important problem remaining to be solved is the lack of structural information on the intermediates between the oxygenated and deoxygenated forms. In order to characterize the intermediate structures, it is necessary to obtain intermediate-state crystals, determine their oxygen saturations and then determine the oxygen saturations of each of their constituent subunits, all of which are challenging issues even now. Here, intermediate forms of the 400 kDa giant Hb from the tubeworm Oligobrachia mashikoi are reported. To overcome the above problems without any artificial modifications to the protein or prosthetic groups, intermediate crystals of the giant Hb were prepared from fully oxygenated crystals by a soaking method. The oxygen saturation of the crystals was measured by in situ observation with a microspectrophotometer using thin plate crystals processed by an ultraviolet laser to avoid saturation of absorption. The oxygen saturation of each subunit was determined by occupancy refinement of the bound oxygen based on ambient temperature factors. The obtained structures reveal the detailed relationship between the structural transition and oxygen dissociation. The dimer subassembly of the giant Hb shows strong correlation with the local structural changes at the heme pockets. Although some local ternary-structural changes occur in the early stages of the structural transition, the associated global ternary-structural and quaternary-structural changes might arise at about 50% oxygen saturation. The models based on coarse snapshots of the allosteric transition support the conventional two-state model of Hbs and provide the missing pieces of the intermediate structures that are required for full understanding of the allosteric nature of Hbs in detail.

X-ray dose-dependent structural changes of the [2Fe-2S] ferredoxin from Chlamydomonas reinhardtii.

Plant-type ferredoxin (Fd) is an electron transfer protein in chloroplast. Redox-dependent structural change of Fd controls its association with and dissociation from Fd-dependent enzymes. Among many X-ray structures of oxidized Fd have been reported so far, very likely a given number of them was partially reduced by strong X-ray. To understand the precise structural change between reduced and oxidized Fd, it is important to know whether the crystals of oxidized Fd may or may not be reduced during the X-ray experiment. We prepared the thin plate-shaped Fd crystals from Chlamydomonas reinhardtii and monitored its absorption spectra during experiment. Absorption spectra of oxidized Fd crystals were clearly changed to that of reduced form in an X-ray dose-dependent manner. In another independent experiment, the X-ray diffraction images obtained from different parts of one single crystal were sorted and merged to form two datasets with low and high X-ray doses. An Fo-Fo map calculated from the two datasets showed that X-ray reduction causes a small displacement of the iron atoms in the [2Fe-2S] cluster. Both our spectroscopic and crystallographic studies confirm X-ray dose-dependent reduction of Fd, and suggest a structural basis for its initial reduction step especially in the core of the cluster.

Structure-affinity relationship study of bleomycins and Shble protein by use of a chemical array.

The photocrosslinked chemical array format is useful not merely for screening protein ligands, but also for gaining insight into structure-affinity relationships (SARs). By probing an array of 2000 natural products, containing 50 bleomycin (BLM) derivatives, with cell lysates that overexpress RFP-fused Shble protein, we successfully observed interactions between Shble protein and BLMs on the array. Among the BLM derivatives, those that had long C-terminal tails were found to bind strongly. The binding signal intensities observed on the chemical array correlated well with the association constants, which were determined by isothermal titration carolimetry (ITC) experiments (r(2)=0.663), showing that the on-chip results were not an artifact of ligand immobilization. In addition to the C-terminal tails, the propionamide moieties in pyrimidoblamic acid (PBA) also appeared to be important for binding. The contributions of the propionamide moieties of PBA to binding were further supported by the X-ray structure of the complex of Shble protein and BLM A(6). These results provide insight into the structural requirements for recognition of BLMs by Shble protein.

[A case of chemo-radiation therapy with high degree of efficacy for esophageal cancer with liver metastasis].

A 78-year-old man underwent a radical resection for esophageal cancer (Stage III) and cardiac gastric cancer (Stage IA) at another hospital 2 years ago. After the operation, he was followed at that hospital. In 2008, abdominal CT scan and FDG-PET/CT revealed a liver tumor. He was referred to our hospital and was diagnosed as esophageal cancer with liver metastasis. He received chemo-radiation therapy (CRT). The regimen was docetaxel hydrate (30 mg/m2, day 1, 8, 29 and 36) and S-1 (60 mg/m2, day 1-14 and day 29-45) with radiation (45 Gy) for liver metastasis. He finished the CRT without any hematotoxicity, liver disorder and non-hematotoxic adverse event (grade 3). Abdominal CT was done 2 months after the end of CRT and revealed that the tumor lesion disappeared completely. The patient is alive for 11 months after the CRT without any evidence of recurrence. The tumor disappeared completely for the last 11 months. We conclude that CRT is safe and very effective for esophageal cancer with liver metastasis.

Species and sex identification of the Korean goral (Nemorhaedus caudatus) by molecular analysis of non-invasive samples.

Korean long-tailed goral (Nemorhaedus caudatus) is one of the most endangered species in South Korea. However, detailed species distribution and sex ratio data on the elusive goral are still lacking due to difficulty of identification of the species and sex in the field. The primary aim of this study was to develop an economical PCR-RFLP method to identify species using invasive or non-invasive samples from five Korean ungulates: goral (N. caudatus), roe deer (Capreolus pygargus), feral goat (Capra hircus), water deer (Hydropotes inermis) and musk deer (Moschus moschiferus). The secondary aim was to find more efficient molecular sexing techniques that may be applied to invasive or non-invasive samples of ungulate species. We successfully utilized PCR-RFLP of partial mitochondrial cytochrome b gene (376 bp) for species identification, and sex-specific amplification of ZFX/Y and AMELX/Y genes for sexing. Three species (goral, goat and water deer) showed distinctive band patterns by using three restriction enzymes (XbaI, StuI or SspI). Three different sexing primer sets (LGL331/335 for ZFX/Y gene; SE47/48 or SE47/53 for AMELX/Y gene) produced sex-specific band patterns in goral, goat and roe deer. Our results suggest that the molecular analyses of non-invasive samples might provide us with potential tools for the further genetic and ecological study of Korean goral and related species.

[Results of hepatic arterial infusion chemotherapy with 5-FU and leucovorin for unresectable liver metastases from colorectal cancer].

PURPOSE: Hepaticarterial infusional(HAI)5-FU chemotherapy, which involves the use of interventional radiology technique, has matured technically in Japan in the 1990's. The antitumor effect of 5-FU is enhanced by combination with leucovorin. This study was performed to evaluate the efficacy and toxicity of HAI 5-FU and leucovorin chemotherapy for patients with unresectable liver metastases from colorectal cancer. METHODS: Treatment was given to 20 patients with unresectable liver metastases from colorectal cancer. The chemotherapy regimen consisted of weekly HAI of 5-FU(1,000 mg/body)and leucovorin(250 mg/body)over five hours. The survival and response rates to the therapy were assessed according to RECIST. Hematologic and non-hematologic toxicity was assessed according to CTCAE v3.0. RESULTS: Combined HAI 5-FU and leucovorin therapy was carried out an average of 27 times. The response rate for liver tumors was 75%, and the median survival time was 22 months. The applied regimen caused only mild adverse events. There was no evidence of myelosuppression except for platelet decrease(grade 3)in a patient with chronic renal failure. CONCLUSION: This HAI approach using 5-FU and leucovorin was effective and the therapy for unresectable liver metastases from colorectal cancer was tolerated well. Therefore the HAI approach should be reconsidered as an effective therapy against this disease in Japan.

[A resected case of postoperative liver metastasis of a gastrointestinal stromal tumor showing complete response after imatinib treatment].

A 71-year-old man visited the hospital complaining of nausea in December 2002. Following a diagnosis of a gastrointestinal stromal tumor (GIST), partial resection of the stomach was performed in January 2003. The tumor was immunohistochemically positive for c-kit and CD34. The tumor size was 6.5 x 5.0 x 4.5 cm with a mitotic index of 25 out of 50 in the high-power field. The pathological diagnosis indicated a high-risk GIST. Treatment with imatinib at a dose of 400 mg/day was started because of liver metastasis of the GIST in January 2004. The liver metastasis was gradually reduced and exhibited cystic change. We considered that there was a complete response without accumulation by FDG-PET in June 2007. An hepatic segmentectomy was performed and imatinib was discontinued in July 2007. Most intratumorale in the specimen underwent hyaline degeneration after pathological examination, but there were viable cells in a portion of the tumor border. Imatinib treatment was resumed because of recurrence in the remnant stomach four months postoperatively owing to imatinib withdrawal. In making a diagnosis at the cell level by FDG-PET, it was difficult to determine the effectiveness of imatinib, and therefore, it is suggested that imatinib treatment must be continued after surgical resection.

Crystal structures of archaerhodopsin-1 and -2: Common structural motif in archaeal light-driven proton pumps.

Archaerhodopsin-1 and -2 (aR-1 and aR-2) are light-driven proton pumps found in Halorubrum sp. aus-1 and -2, which share 55-58% sequence identity with bacteriorhodopsin (bR), a proton pump found in Halobacterium salinarum. In this study, aR-1 and aR-2 were crystallized into 3D crystals belonging to P4(3)2(1)2 (a = b = 128.1 A, c = 117.6 A) and C222(1) (a = 122.9 A, b = 139.5 A, c = 108.1 A), respectively. In both the crystals, the asymmetric unit contains two protein molecules with slightly different conformations. Each subunit is composed of seven helical segments as seen in bR but, unlike bR, aR-1 as well as aR-2 has a unique omega loop near the N terminus. It is found that the proton pathway in the extracellular half (i.e. the proton release channel) is more opened in aR-2 than in aR-1 or bR. This structural difference accounts for a large variation in the pKa of the acid purple-to-blue transition among the three proton pumps. All the aromatic residues surrounding the retinal polyene chain are conserved among the three proton pumps, confirming a previous argument that these residues are required for the stereo-specificity of the retinal isomerization. In the cytoplasmic half, the region surrounded by helices B, C and G is highly conserved, while the structural conservation is very low for residues extruded from helices E and F. Structural conservation of the hydrophobic residues located on the proton uptake pathway suggests that their precise arrangement is necessary to prevent a backward flow of proton in the presence of a large pH gradient and membrane potential. An empty cavity is commonly seen in the vicinity of Leu93 contacting the retinal C13 methyl. Existence of such a cavity is required to allow a large rotation of the side-chain of Leu93 at the early stage of the photocycle, which has been shown to accompany water translocation across the Schiff base.

Identification of DR9-restricted XAGE antigen on lung adenocarcinoma recognized by autologous CD4 T-cells.

We previously demonstrated a dominant IgG response against XAGE-1b antigen in a lung cancer patient by serological analysis of antigens by recombinant expression cloning (SEREX) analysis using a cDNA library from the autologous OU-LU-6 tumor cell line. In this study, we investigated recognition of XAGE-1b on OU-LU-6 tumor by the patient CD4-expressing tumor-infiltrating lymphocytes (CD4 TIL). The response of CD4 TIL obtained from malignant pleural effusion was determined against autologous OU-LU-6 tumor cells and XAGE-1b mRNA-transfected PHA-stimulated CD4 T-cells (T-APC) from healthy individuals sharing HLA-DR with the patient by performing IFNgamma secretion and ELISPOT assays. The patient CD4 TIL recognized OU-LU-6 in an HLA-DR-restricted manner and XAGE-1b mRNA-transfected T-APC derived from DRB1 *0901-sharing healthy donor (HD)1 and HD2, but not DRB1 *1101-sharing HD3 or HD4. Epitope analysis using 17 18-mer peptides with 12 overlapping amino acids revealed that the CD4 TIL recognized XAGE-1b 33-49. The findings suggest that the patient CD4 T-cells recognized the XAGE-1b 33-49-related epitope on autologous OU-LU-6 tumor cells in a manner restricted by DR *0901.