A prospective examination of circulating tumor cell profiles in non-small-cell lung cancer molecular subgroups.

BACKGROUND: We report the first study examining the clinical, numerical and biological properties of circulating tumor cells according to molecular subtypes of non-small-cell lung cancer. PATIENTS AND METHODS: 125 patients with treatment-naïve stage IIIb-IV NSCLC were prospectively recruited for CellSearch analysis. Anti-vimentin antibody was included for examination of CTCs to assess their mesenchymal character. Associations of total CTCs and vimentin-positive (vim +) CTCs with clinical characteristics, tumor genotype, and survival were assessed. RESULTS: 51/125 patients (40.8%) were total CTC+ and 26/125 (20.8%) were vim CTC+ at baseline. Multivariate analysis showed patients with ≥5 total CTCs had significantly reduced OS (HR 0.55, 95% CI 0.33-0.92, P = 0.022) but not PFS (HR 0.68, 95% CI 0.42-1.1, P = 0.118) compared to patients with <5 total CTCs. No OS difference was evident between vim+ CTC and vim-negative CTC patients overall (HR 1.24, 95% CI 0.67-2.28, P = 0.494), but after subdivision according to NSCLC driver mutation, we found an increase of vim+ CTCs in the EGFR-mutated subgroup (N = 21/94 patients; mean 1.24 vs 1.22 vim+ CTCs, P = 0.013), a reduction of total CTCs in the ALK-rearranged subgroup (N = 13/90 patients; mean 1.69 vs 5.82 total CTCs, P = 0.029), and a total absence of vim+ CTCs in KRAS-mutated adenocarcinomas (N = 19/78 patients; mean 0 vs 1.4 vim+ CTCs, P = 0.006). CONCLUSIONS: We validate that the baseline presence of ≥5 total CTCs in advanced NSCLC confers a poor prognosis. CTCs from EGFR-mutant NSCLC express epithelial-mesenchymal transition characteristics, not seen in CTCs from patients with KRAS-mutant adenocarcinoma.

One-stage extreme lateral interbody fusion and percutaneous pedicle screw fixation in lumbar spine tuberculosis.

OBJECTIVES: We explored the efficacy of minimal invasive surgery including one-stage debridement and intervertebral fusion through extreme lateral channel (XLIF) combined with lateral or percutaneous posterior pedicle screw fixation for the treatment of lumbar spine tuberculosis. METHODS: Twenty two patients with lumbar tuberculosis who underwent surgery with XLIF technique and internal fixation were included in the study. Their data about operative time, intraoperative blood loss, bone fusion, kyphosis correction, and clinical recovery were retrospectively collected and analyzed. RESULTS: The mean intraoperative blood loss was 249.8±27.8 ml and the operative time 347.5±20.7 min. At the final follow-up, 11 to 15 months postoperatively, ESR and CRP were normal and pain (VAS) and Oswestry disability index (ODI) were significantly reduced (23.0±-3.1 vs 0.6±-0.7 and 57.2±-1.6 vs 6.4±-1.2 respectively) compared to preoperative values. Progression of the kyphotic deformity was effectively prevented (mean Cobb angle 23.9° +/-1.9° vs 24.5° +/-1.4°, P>0.05). There was one failure of the fixation associated to poor therapy adherence. All the patients showed neurological recovery. CONCLUSION: Debridement and interbody fusion by extreme lateral channel combined with lateral or percutaneous posterior pedicle screw fixation effectively retained the spine stability and provided clinical and neurologic recovery in selected patients with lumbar spine tuberculosis.

Activating oxidative phosphorylation by a pyruvate dehydrogenase kinase inhibitor overcomes sorafenib resistance of hepatocellular carcinoma.

BACKGROUND: Sorafenib is the only drug approved for the treatment of hepatocellular carcinoma (HCC). The bioenergetic propensity of cancer cells has been correlated to anticancer drug resistance, but such correlation is unclear in sorafenib resistance of HCC. METHODS: Six sorafenib-naive HCC cell lines and one sorafenib-resistant HCC cell line (Huh-7R; derived from sorafenib-sensitive Huh-7) were used. The bioenergetic propensity was calculated by measurement of lactate in the presence or absence of oligomycin. Dichloroacetate (DCA), a pyruvate dehydrogenase kinase (PDK) inhibitor, and siRNA of hexokinase 2 (HK2) were used to target relevant pathways of cancer metabolism. Cell viability, mitochondrial membrane potential, and sub-G1 fraction were measured for in vitro efficacy. Reactive oxygen species (ROS), adenosine triphosphate (ATP) and glucose uptake were also measured. A subcutaneous xenograft mouse model was used for in vivo efficacy. RESULTS: The bioenergetic propensity for using glycolysis correlated with decreased sorafenib sensitivity (R(2)=0.9067, among sorafenib-naive cell lines; P=0.003, compared between Huh-7 and Huh-7 R). DCA reduced lactate production and increased ROS and ATP, indicating activation of oxidative phosphorylation (OXPHOS). DCA markedly sensitised sorafenib-resistant HCC cells to sorafenib-induced apoptosis (sub-G1 (combination vs sorafenib): Hep3B, 65.4±8.4% vs 13±2.9%; Huh-7 R, 25.3± 5.7% vs 4.3±1.5%; each P<0.0001), whereas siRNA of HK2 did not. Sorafenib (10 mg kg(-1) per day) plus DCA (100 mg kg(-1) per day) also resulted in superior tumour regression than sorafenib alone in mice (tumour size: -87% vs -36%, P<0.001). CONCLUSION: The bioenergetic propensity is a potentially useful predictive biomarker of sorafenib sensitivity, and activation of OXPHOS by PDK inhibitors may overcome sorafenib resistance of HCC.

Immunoprotective Leishmania major synthetic T cell epitopes.

Using the predictive algorithm of Rothbard and Taylor (1988. EMBO J. 7:93) and the primary structure of gp63 (Button, L., and M.R. McMaster. 1988. J. Exp. Med. 167:724; Miller, R.A., S.G. Reed, and M. Parsons. 1990. Mol. Biochem. Parasitol. 39:267) we have been able to delineate the structures of a number of gp63 T-cell epitopes which stimulate the proliferation of CD4+ cells. One of these synthetic antigens, inoculated subcutaneously with adjuvant, was shown to specifically induce proliferation of the Th1 subset and provided immunoprotection against two species of Leishmania parasites.

Different radiation techniques to deliver therapeutic dose to the axilla in patients with sentinel lymph node-positive breast cancer: Doses, techniques challenges and clinical considerations.

PURPOSE: To evaluate the coverage of different levels of axillary lymph nodes and organs at risk according to the field design of AMAROS study (levels I-II-III-IV), breast tangents with supraclavicular and infraclavicular fields (levels II-III-IV) and high tangent fields to the breast after breast-conserving surgery. MATERIALS AND METHODS: We delineated the axillary lymph nodes levels I-IV in 34 patients treated with breast-conserving surgery and sentinel lymph nodes biopsy. Field design according to AMAROS study - levels I-IV in patients without axillary dissection - as well as irradiation of levels II-IV used in N+ patients after axillary dissection, and also high tangent fields was simulated. Mean dose levels and volumes covered by 95% or 80% isodoses were evaluated. Doses to ipsilateral lung, heart and brachial plexus were compared. Paired t test was used. RESULTS: AMAROS study and levels II-IV plans delivered therapeutic dose to high axilla (levels II-IV), but the high tangent fields showed inefficacy to cover these volumes, P<0.001). In terms of organs at risk, especially, ipsilateral lung, AMAROS study plan was found to significantly increase the volume receiving at least 10Gy (I-IV:46.8%, II-IV: 39%), but also the volume receiving at least 20Gy (I-IV: 39.3%, II-IV: 31.3%), and V30Gy (I-IV: 34.2% vs II-IV: 26.1%), as well as the mean dose (I-IV: 18.6Gy, II-IV: 15.2Gy, P<0.001). CONCLUSIONS: The omission of axillary dissection and the axilla irradiation need is associated with high dose irradiation of the lungs, and with higher toxicity. The indication of axillary dissection or irradiation of low axilla could be individualized in relation with individual comorbidities and factors of risk.

Outcome of postmastectomy radiotherapy after primary systemic treatment in patients with clinical T1-2N1 breast cancer.

PURPOSE: The role of postmastectomy radiotherapy following primary systemic treatment in patients with clinical T1-2N1 breast cancer remains a controversial issue. The purpose of this study was to evaluate the benefit of postmastectomy radiotherapy following primary systemic treatment. PATIENTS AND METHODS: Between 2005 and 2012, in two independent institutions, female patients with T1-2N1 breast cancer receiving primary systemic treatment followed by mastectomy and lymph node dissection because bad response, then treated with or without chest wall and regional lymph node irradiation have been studied retrospectively. The patients received normofractionated radiotherapy using 3D conformal photons or electron techniques. Locoregional recurrence-free survival, distant metastasis-free survival and disease-free survival were calculated using Kaplan-Meier method. Univariate analysis of potential prognostic factors was performed using log-rank test. RESULTS: Eighty-eight patients have been studied. Of them, 75 patients received postmastectomy radiotherapy. At surgery, 53 patients achieved ypN0. Median follow-up was 67 months. Postmastectomy radiotherapy significantly improved locoregional recurrence-free survival, with a 5-year rate of 96.9% versus 78.6% in the group that did not have postmastectomy radiotherapy. In the subgroup of 53 patients achieving ypN0, postmastectomy radiotherapy improved locoregional recurrence-free survival (a 5-year rate of 94.7% vs. 72.9%), distant metastasis-free survival (a 5-year rate of 92.8% vs. 75%) and disease-free survival (a 5-year rate of 92.9% vs. 62.5%). By univariate analysis, postmastectomy radiotherapy was the only significant prognostic factor affecting locoregional recurrence-free survival. CONCLUSIONS: For patients with clinical T1-2N1 disease, postmastectomy radiotherapy could significantly improve locoregional recurrence-free survival after primary systemic treatment and be even more therapeutic in the subgroup of patients with good response for primary systemic treatment by improving locoregional recurrence-free, distant metastasis-free and disease-free survival. Larger prospective studies are needed to confirm our findings.

Expression of lamin A/C protein in degenerated human intervertebral disc.

OBJECTIVE: This study aimed to evaluate the expression characteristics of lamin A/C proteins in intervertebral disc degeneration (IVD) specimens from patients with different degeneration grades. Lamin A/C proteins have been shown to result in age-related changes in the osteoarticular system. However, the expression characteristics of these nuclear proteins in degenerated human IVD tissues have not been explored previously. PATIENTS AND METHODS: Degenerated human IVD tissues were obtained during spinal surgery. Articular cartilage samples after total knee replacement surgery were used as controls. Sections of these tissues were stained with hematoxylin and eosin, Masson, safranin O, and immunostained using lamin A/C antibody. Western blot was performed to evaluate lamin A/C expression in IVD tissues. Lamin A/C expression was analyzed based on different degeneration grades. RESULTS: In patients with IVD degeneration, mild or moderate degenerative discs contained high amounts of lamin A/C proteins. Lamin A/C expression was primarily localized in the nuclear envelope of IVD cells, and associated with apoptosis in cell nuclei, as determined by immunostaining and TUNEL assay. CONCLUSIONS: This paper is the first to report that lamin A/C proteins are present in IVD tissues and its expression may be related to disc degeneration.

Lenalidomide as second-line therapy for advanced hepatocellular carcinoma: exploration of biomarkers for treatment efficacy.

BACKGROUND: Lenalidomide has immunomodulatory and anti-angiogenic effects and showed moderate anti-tumour efficacy in patients with. advanced hepatocellular carcinoma (HCC) AIM: To explore potential biomarkers of lenalidomide efficacy as second-line therapy for HCC. METHODS: Eligible patients were diagnosed with advanced HCC, documented progression on sorafenib, and Child-Pugh class A liver function. Patients received 25 mg/day lenalidomide orally on days 1-21 every 4 weeks. The primary endpoint was 6 month progression-free survival rate. Early α-fetoprotein response was defined as a > 20% decline of α-fetoprotein levels from baseline within the first 4 weeks of treatment. Vascular response, evaluated using dynamic contrast-enhanced magnetic resonance imaging, was defined as a > 40% decline in Ktrans after 2 weeks of treatment. The percentage of peripheral blood lymphocyte subsets were also analysed. RESULTS: Fifty-five patients were enrolled. The response rate was 13%, and the disease-control rate was 53%. The 6 month progression-free survival rate was 9.1%. The median progression-free and overall survival was 1.8 months and 8.9 months respectively. Early α-fetoprotein response was significantly associated with higher disease-control rate (76% vs 22%, P = .001) and longer progression-free survival (P = .020). Vascular response was not associated with any treatment outcomes. Patients with a high pre-treatment B cell percentage were more likely to have disease control (70% vs 36%, P = .010) and exhibited longer progression-free survival (P < .001) and overall survival (P = .042). CONCLUSIONS: Lenalidomide exhibited moderate activity as second-line therapy for advanced HCC. Its immunomodulatory effects should be further explored (www.clinicaltrials.gov NCT01545804).

Hepatocellular carcinoma cells containing hepatitis B virus X protein have enhanced invasive potential conditionally.

AIMS: To establish a sustaining hepatitis B virus X protein expressed Chang liver cell line and to explore their biological behaviours of invasive potential induced by hepatitis B virus X protein. METHODS: Polymerase chain reaction was used to amplify the HBx gene from the whole hepatitis B virus genome. The gene was then subcloned into the eukaryotic expression vector pcDNA3.1 to construct the pcDNA3.1-HBx plasmid. Gene transfection mediated by Lipofectamine was used to introduce the plasmid into the human liver cell line Chang, and stable expression of the HBx gene was detected. RESULTS: HBx gene was cloned from the transfected Chang liver cells by reverse transcription-polymerase chain reaction, and confirmed by electrophoresis. The stably transfected Chang cells expressing HBx with malignant characteristics were verified and compared with control cells in terms of their growth curves, clonogenicity, wound healing abilities, migration and metastasis. CONCLUSION: The stabilising human liver cell lines Chang liver containing HBx gene expression have been established successfully. The invasive potential of Chang cells was conditionally enhanced by HBx transfection.

HCHs and DDTs in sediment-dwelling animals from the Yangtze Estuary, China.

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2-5.5 ng g(-1) and averaged 3.5 ng g(-1) in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g(-1), with a mean of 34.5 ng g(-1). In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g(-1) and averaged 13.8 ng g(-1), whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g(-1) with a mean value of 5.9 ng g(-1). The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.

HCHs and DDTs in salt marsh plants (Scirpus) from the Yangtze estuary and nearby coastal areas, China.

HCHs and DDTs in salt marsh plants taken from intertidal flats in the Yangtze estuary and coastal area in April and July 2002 were determined by GC-ECD. A significant seasonal effect was observed for HCHs and DDTs in sources and concentration levels in different sample types including above-ground tissues and roots as well as the whole plants and rhizospheric sediments. The results indicated that the concentration of t-HCH was higher in the above-ground tissues than in their roots in April; however, the partitioning of DDTs between contaminated sediments and the roots showed the higher concentrations of t-DDT in their roots. HCHs and DDTs concentration levels were higher in above-ground tissues than in roots in July. BCFs of HCHs and DDTs exhibited lower values with higher levels of contaminants in sediments, and higher values with lower levels in sediments.

Organic carbon and nitrogen stable isotopes in the intertidal sediments from the Yangtze Estuary, China.

The natural isotopic compositions and C/N elemental ratios of sedimentary organic matter were determined in the intertidal flat of the Yangtze Estuary. The results showed that the ratios of carbon and nitrogen stable isotopes were respectively -29.8 per thousand to -26.0 per thousand and 1.6 per thousand-5.5 per thousand in the flood season (July), while they were -27.3 per thousand to -25.6 per thousand and 1.7 per thousand-7.8 per thousand in the dry season (February), respectively. The delta(13)C signatures were remarkably higher in July than in February, and gradually increased from the freshwater areas to the brackish areas. In contrast, there were relatively complex seasonal and spatial changes in stable nitrogen isotopes. It was also reflected that delta(15)N and C/N compositions had been obviously modified by organic matter diagenesis and biological processing, and could not be used to trace the sources of organic matter at the study area. In addition, it was considered that the mixing inputs of terrigenous and marine materials generally dominated sedimentary organic matter in the intertidal flat. The contribution of terrigenous inputs to sedimentary organic matter was roughly estimated according to the mixing balance model of stable carbon isotopes.

Effects of particle size and physical form of diets on mast cell numbers, histamine, and stem cell factor concentration in the small intestine of broiler chickens.

The aim of this study was to investigate the hypothesis that particle size and diet form may affect the growth of mast cells and histamine release from the small intestine of broiler chickens. A total of 288, day-old male broiler chicks were randomly allocated to 1 of 4 corn-soy diets in a 2 x 2 factorial design. The factors included particle size (coarse vs. fine) and physical form (mash vs. pellet). The birds were housed in 90 x 60 cm pens containing 12 birds, and each treatment contained 6 replicate pens of birds from d 1 to 22. On d 22, 6 broilers from each treatment were slaughtered. Tissues from the small intestine (duodenum, jejunum, and ileum) were obtained to quantify mast cells using the toluidine blue staining technique. The results showed that mast cells in the jejunum were concentrated in the upper part of the villus in birds fed the coarsely ground mash diet, whereas mast cells were evenly distributed throughout the intestine in birds fed the other 3 diets. The number of mast cells was significantly lower in the duodenum (P = 0.04), jejunum (P < 0.01), and ileum (P = 0.01) of birds fed coarsely ground diets compared with finely ground diets, and there was no difference in mast cell numbers between birds fed mashed or pelleted diets at any site in the intestine. The histamine content (P = 0.02) and stem cell factor concentration (P = 0.03) were markedly lower in the jejunum of birds that were fed coarsely ground diets compared with finely ground diets. The stem cell factor concentration in the duodenum (P < 0.01) and jejunum (P = 0.05) was higher in birds fed pelleted compared with mash diets. The overall results of this experiment suggest that particle size and diet form affect mast cell number and histamine content in the small intestine by regulation of stem cell factor concentration.

Erythrocyte gamma-glutamylcysteine synthetase from normal and low-glutathione sheep.

gamma-Glutamylcysteine synthetase (L-glutamate:L-cysteine gamma-ligase (ADP-forming), EC 6.3.2.2) was purified from the erythrocytes of normal and low-glutathione sheep. The molecular weight (78 000), pH optimum (pH 7), substrate specificity, inhibition constant for glutathione (0.44-0.50 mM), electrophoretic mobility, and heat stability were similar for the purified enzyme from both sources. Using immunological techniques, the specific activity of gamma-glutamylcysteine synthetase from low-glutathione sheep was lower than that from normal sheep.

Regulation of TNF-related apoptosis-inducing ligand-mediated death-signal pathway in human beta cells by Fas-associated death domain and nuclear factor kappaB.

Transfectants of human CM and NES2Y beta cell lines and primary islets transfected by FADD-DN (dominant-negative form of Fas-associated death domain), a mutant of FADD and/or a superrepressor of nuclear factor kappaB (NF-kappaB) (AdIkappaB(SA)2), were examined for their susceptibility to the TRAIL (TNF-related apoptosis-inducing ligand)-induced death signal pathway, compared with controls, wild-type cells, and vector transfectants in caspase fluorescence, Western blot, electrophoretic mobility shift, apoptosis, and cytotoxicity assays. FADD-DN inhibited caspase-8 activation induced by TRAIL in the transfectants of CM and NES2Y cells. TRAIL-induced apoptosis and cytotoxicity to the FADD-DN transfectants were decreased in comparison to those responses in controls (CM, p < 0.01 and p < 0.01; NES2Y, p < 0.05, and p < 0.02, respectively). When CM, NES2Y, and primary islet cells were transfected by AdIkappaB(SA)2, TRAIL-induced IkappaB degradation and nuclear translocation of NF-kappaB p50/p65 were blocked. TRAIL-induced apoptosis and cytotoxicity to AdIkappaB(SA)2 transfectants of these cells were also reduced (CM, p < 0.02 and p < 0.02; NES2Y, p < 0.01 and p < 0.01, respectively, and islet p < 0.01 for cytotoxicity). Finally, cytotoxicity induced by TRAIL in CM and NES2Y cells transfected with both FADD-DN and AdIkappaB(SA)2 was reduced, compared with that observed in these cells transfected with either FADD-DN alone or AdIkappaB(SA)2 alone, suggesting that FADD and NF-kappaB have synergistic proapoptotic regulatory effects on the susceptibility of beta cell lines and islet cells to TRAIL-induced destruction.

A new categorization of HLA DR alleles on a functional basis.

In this analysis, we introduce a new categorization of HLA DR alleles which are important members of HLA class II genes encoding cell surface glycoproteins that function to present antigenic peptides to T cells. We have grouped all HLA DR molecules into seven different functional categories on the basis of their ability to bind and present antigenic peptides to T cells and their association with susceptibility or resistance to disease. This novel categorization of DR alleles on the basis of function allows for the prediction of seven similar subregion structures (supertypes or supermotifs) within pocket 4 of HLA DR peptide binding groove as the molecular basis for grouping these alleles. The physicochemical characteristics of HLA DR supertype residues, charge in particular, may influence the selectivity for binding peptide, dominate promiscuous T-cell recognition of antigenic peptides, and affect HLA DR disease associations. To rationalize the functional categories of DR alleles, we have further combined the seven DR supertype patterns into three groups based on the charges of residues within the supertypes. Grouping HLA DR alleles into functional categories may assist in understanding the mechanistic basis of autoimmunity, resolving current paradoxes in HLA disease associations, and developing new immunotherapy strategies.

CD4+ and CD8+ T-cell clones from congenital rubella syndrome patients with IDDM recognize overlapping GAD65 protein epitopes. Implications for HLA class I and II allelic linkage to disease susceptibility.

To fully characterize human glutamic acid decarboxylase (GAD)65 protein T-cell epitopes associated with insulin-dependent diabetes mellitus (IDDM), CTL clones specific to GAD65 protein antigens were isolated from two congenital rubella syndrome (CRS)-associated IDDM patients. Overlapping nonamer T-cell epitopes recognized by both CD4+ or CD8+ CTL clones within peptides GAD65(252-266) and GAD65(274-286) were identified as sequences bounded by GAD65(255-266) with 6/9 overlapping residues, and GAD65(276-285) with 8/9 overlapping residues, respectively, using two panels of overlapping peptide analogs in cytotoxicity assays. HLA restrictive elements of the T-cell clones were also identified using a panel of B cell lines with different HLA phenotypes as targets in cytotoxicity assays. The antigenic GAD65 peptides elicited cytotoxic responses of peptide-specific CD4+ T-cell clones in the context of HLA DRB1*0404. The CD8+ T-cell clone specific to GAD65(255-263) was found to be restricted by HLA A3 and A11. Similarly, the CD8+ T-cell clone specific to GAD65(277-285) killed peptide-sensitized target cells expressing HLA B35 and B15. The observed HLA restriction of these overlapping epitopes implies that a tandem of [DRB1*0404-A11(3)] and/or a tandem of [DRB1*0404-B35(15)] might predispose CRS patients to development of IDDM.

Promiscuous T-cell recognition of a rubella capsid protein epitope restricted by DRB1*0403 and DRB1*0901 molecules sharing an HLA DR supertype.

Two T cell clones derived from different donors with HLA-DRB1*0403 or DRB1*0901 phenotype recognize a rubella capsid peptide, C(265-273) in the context of several different HLA-DR molecules in addition to DRB1*0403 and DRB1*0901. All DR molecules restricting the T-cell clones have in common residues, R or Q at position beta 70, R at position beta 71, and E at position beta 74 in pocket '4' of the DR peptide binding groove, suggesting that a DR subregion structure or supertype, "Q/RRE" underlies the promiscuous T-cell recognition of this peptide. Single amino acid substituted analogs of peptide C(263-275) at anchor position 4 for natural residue R were tested for their ability to induce clonal T-cell cytotoxic responses. The results indicated that a positively charged residue, R or K, was required for T-cell recognition, suggesting a possible mechanism of electrostatic interactions between the negatively charged residue E at position beta 74 of these DR molecules and the positively charged residue at anchor position 4 of the peptide in T-cell recognition.

Analysis of overlapping T- and B-cell antigenic sites on rubella virus E1 envelope protein. Influence of HLA-DR4 polymorphism on T-cell clonal recognition.

A CTL antigenic site located between residues 273 and 291 of the E1 envelope protein of RV was identified by 51Cr-release assays employing SPs. Two E1-specific CTL clones were examined for immune recognition of RV wild-type and attenuated vaccine strains and recombinant E1 protein. The exact sequence (273-284) recognized by both clones was delineated by using truncated and overlapping SPs covering these residues. The defined T-cell site overlapped almost completely with a virus neutralizing antibody-binding site previously identified with mouse monoclonal and human antibodies. A series of single aa-substituted SP analogues of E1(273-284) was used to define residues critical for T-cell recognition. Using EBV-BL displaying different HLA-DR haplotypes and -DR4 subtypes as targets to determine MHC class II restriction elements, immune recognition by both T-cell clones was shown to be associated with HLA-DR4. Three HLA-DR4 subtypes (DR4Dw13A, DR4Dw13B, and DR4KT2) sharing a common residue, glutamic acid at position 74 in their beta 1 chains, were able to present SP E1(273-284) to the T-cell clones.