A single nine-amino acid peptide induces virus-specific, CD8+ human cytotoxic T lymphocyte clones of heterogeneous serotype specificities

It is generally accepted that virus-specific CD8+ cytotoxic T lymphocytes (CTLs) recognize nine-amino acid peptides in conjunction with HLA class I molecules. We recently reported that dengue virus-specific CD8+ CTLs of two different serotype specificities, which were established by stimulation with dengue virus, recognize a single nine-amino acid peptide of the nonstructural protein NS3 of dengue virus type 4 (D4V) in an HLA-B35-restricted fashion. To further analyze the relationships between the serotype specificities of T cells and the amino acid sequence of the recognized peptides, we examined the ability of this viral peptide D4.NS3.500-508 (TPEGIIPTL) to stimulate T lymphocytes of an HLA-B35-positive, dengue virus type 4-immune donor. Peptide stimulation of the PBMC generated dengue virus-specific, HLA-B-35-restricted CD8+ CTL clones. These clones lysed dengue virus-infected autologous cells, as well as autologous target cells pulsed with this peptide. Four patterns of dengue virus serotype specificities were demonstrated on target cells infected with dengue-vaccinia recombinant viruses or pulsed with synthetic peptides corresponding to amino acid sequences of four dengue virus serotypes. Two serotype-specific clones recognized only D4V. Three dengue virus subcomplex-specific clones recognized D1V, D3V, and D4V, and one subcomplex-specific clone recognized D2V and D4V. Three dengue virus serotype-cross-reactive clones recognized D1V-D4V. Thus, a single nine-amino acid peptide induces proliferation of a heterogeneous panel of dengue virus-specific CD8+ CTL clones that are all restricted by HLA-B35 but have a variety of serotype specificities. Peptides that contain a single amino acid substitution at each position of D4.NS3.500-508 were recognized differently by the T cell clones. These results indicate that a single epitope can be recognized by multiple CD8+ CTLs that have a variety of serotype specificities, but the manner of recognition by these multiple CTLs is heterogeneous

Somatic molecular analysis augments cytologic evaluation of pancreatic cyst fluids as a diagnostic tool

Objective: Better tools are needed for early diagnosis and classification of pancreatic cystic lesions (PCL) to trigger intervention before neoplastic precursor lesions progress to adenocarcinoma. We evaluated the capacity of molecular analysis to improve the accuracy of cytologic diagnosis for PCL with an emphasis on non-diagnostic/negative specimens. Design: In a span of 7 years, at a tertiary care hospital, 318 PCL endoscopic ultrasound-guided fine needle aspirations (EUS-FNA) were evaluated by cytologic examination and molecular analysis. Mucinous PCL were identified based on a clinical algorithm and 46 surgical resections were used to verify this approach. The mutation allele frequency (MAF) of commonly altered genes (BRAF, CDKN2A, CTNNB1, GNAS, RAS, PIK3CA, PTEN, SMAD4, TP53 and VHL) was evaluated for their ability to identify and grade mucinous PCL. Results: Cytology showed a diagnostic sensitivity of 43.5% for mucinous PCL due in part to the impact of non-diagnostic (28.8%) and negative (50.5%) specimens. Incorporating an algorithmic approach or molecular analysis markedly increased the accuracy of cytologic evaluation. Detection of mucinous PCL by molecular analysis was 93.3% based on the detection of KRAS and/or GNAS gene mutations (p = 0.0001). Additional genes provided a marginal improvement in sensitivity but were associated with cyst type (e.g. VHL) and grade (e.g. SMAD4). In the surgical cohort, molecular analysis and the proposed algorithm showed comparable sensitivity (88.9% vs. 100%). Conclusions: Incorporating somatic molecular analysis in the cytologic evaluation of EUS-FNA increases diagnostic accuracy for detection, classification and grading of PCL. This approach has the potential to improve patient management

Multicenter evaluation of the clinical utility of laparoscopy-assisted ERCP in patients with Roux-en-Y gastric bypass

Background and Aims The obesity epidemic has led to increased use of Roux-en-Y gastric bypass (RYGB). These patients have an increased incidence of pancreaticobiliary diseases yet standard ERCP is not possible due to surgically altered gastroduodenal anatomy. Laparoscopic-ERCP (LA-ERCP) has been proposed as an option but supporting data are derived from single center small case-series. Therefore, we conducted a large multicenter study to evaluate the feasibility, safety, and outcomes of LA-ERCP. Methods This is retrospective cohort study of adult patients with RYGB who underwent LA-ERCP in 34 centers. Data on demographics, indications, procedure success, and adverse events were collected. Procedure success was defined when all of the following were achieved: reaching the papilla, cannulating the desired duct and providing endoscopic therapy as clinically indicated. Results A total of 579 patients (median age 51, 84% women) were included. Indication for LA-ERCP was biliary in 89%, pancreatic in 8%, and both in 3%. Procedure success was achieved in 98%. Median total procedure time was 152 minutes (IQR 109-210) with median ERCP time 40 minutes (IQR 28-56). Median hospital stay was 2 days (IQR 1-3). Adverse events were 18% (laparoscopy-related 10%, ERCP-related 7%, both 1%) with the clear majority (92%) classified as mild/moderate whereas 8% were severe and 1 death occurred. Conclusion Our large multicenter study indicates that LA-ERCP in patients with RYGB is feasible with a high procedure success rate comparable with that of standard ERCP in patients with normal anatomy. ERCP-related adverse events rate is comparable with conventional ERCP, but the overall adverse event rate was higher due to the added laparoscopy-related events

Dengue virus-specific, human CD4+ cytotoxic T lymphocytes generated in short-term culture

We previously reported cytotoxic activity of dengue virus-specific CD4+ CD8- T cell clones established in long-term in vitro culture. In the present experiments we tried to determine whether dengue virus-specific CD4+ CD8- CTL3 are present in short-term bulk cultures. Peripheral blood mononuclear cells (PBMC)3 from a donor who had been immunized with an experimental live attenuated dengue 1 vaccine 8 months earlier were used. PBMC were incubated with noninfectious dengue 1 antigen (Ag)3 for 7 days, and were examined for dengue 1-specific cytotoxic activity. PBMC cultured with dengue 1 Ag lysed autologous lymphoblastoid cell line (LCL)3 pulsed with noninfectious dengue 1 Ag, but did not lyse LCL pulsed with Ag of other dengue serotype, West Nile virus, or yellow fever virus, or control Ag. Treatment of cultured PBMC with monoclonal antibody to CD3 or CD4 and complement abrogated the cytotoxic activity but treatment with a monoclonal antibody to CD8 and complement did not. A time course study showed that dengue 1 Ag-specific CTL were first detected in 5 day cultures. Lysis of target cells by these CD4+ CTL were restricted by HLA class II, and HLA DQw1 and HLA DRw52 were determined to be the restriction molecules. These results indicate that dengue virus-specific CD4+ CD8- CTL are generated in short-term bulk cultures as well as in long-term-cultured cell lines, and support the concept that CD4+ CTL may be generated in vivo during infection

Ubiquitin as a marker of cell injury in nonalcoholic steatohepatitis

Ubiquitin (UB), an intracellular protein that binds to other proteins to target them for proteolysis, is associated with Mallory hyalin (MH), which supports a biopsy diagnosis of nonalcoholic steatohepatitis (NASH). We analyzed 54 liver biopsy specimens from 49 patients with a clinical diagnosis of NASH for immunoreactive UB and multiple features of necroinflammation, fibrosis, and Prussian blue-positive iron to determine whether the presence of immunoreactive UB increases detection of MH or correlates with other features of cell injury or mutations of the HFE gene. MH and UB were graded. Analysis for HFE gene mutations was performed in 48 patients. Biopsy diagnoses were distributed as follows: NASH, 42; steatosis, 10; and nonspecific changes, 2. UB was present in 20 specimens and MH in 23. Of 31 specimens with 0 MH, 6 had UB; of 14 with 1 + (questionable) MH, 7 had 1+ or 2+ UB. UB correlated positively and significantly with the diagnosis and grade of NASH, presence of MH, cell swelling, lobular inflammation, and fibrosis. Immunostaining for UB may enhance detection of MH in questionable cases, support the diagnosis of NASH, and indicate which patients may be at risk for progression of disease

Partial agonist effect influences the CTL response to a heterologous dengue virus serotype

Activation of dengue serotype-cross-reactive memory CTL during secondary dengue virus (DV) infection is thought to be important in the pathogenesis of dengue hemorrhagic fever. To model this effect, we studied the CTL responses to DV types 2 (D2V) and 3 (D3V) in PBMC from an individual previously infected with D3V. DV-specific CD8+ CTL from this donor recognized two HLA-B62-restricted epitopes on the NS3 protein, aa 71-79 (SVKKDLISY) and 235-243 (AMKGLPIRY). Both D3V-specific and D2V/D3V-cross-reactive CTL clones were detected for each epitope; all D2V-reactive CTL clones could lyse D2V-infected autologous cells. CTL responses to both epitopes were detected in bulk cultures stimulated with D3V, but PBMC stimulated with D2V recognized only the 235-243 epitope. IFN-gamma enzyme-linked immunospot assay showed that the D2V (71-79) peptide (DVKKDLISY) did not efficiently activate T cells. Analysis of a CTL clone suggests that the D2V (71-79) peptide acts as a partial agonist, able to sensitize target cells for lysis and inducing only minimal proliferation at high concentrations. These results suggest that variant peptide sequences present in the heterologous DV serotype can influence the CTL response in vivo during secondary DV infection

Analysis of plasma viral RNA levels during acute dengue virus infection using quantitative competitor reverse transcription-polymerase chain reaction

There is increasing recognition of the potential importance of viral burden in the pathogenesis of dengue hemorrhagic fever (DHF). There is little data available, however, describing the kinetics of viral replication in humans with natural dengue virus (DV) infection. Standard procedures for measuring titers of infectious virus in clinical specimens are either laborious or insensitive. We developed a method for measurement of DV RNA in plasma samples based on reverse transcription-polymerase chain reaction (RT-PCR) using a mutant RNA target as a competitor. This technique was reproducible and accurate for samples containing any of the four DV serotypes, and could be applied to samples containing as few as 250 copies of RNA per reaction. We examined plasma viral RNA levels in 80 children with acute DV infection; sequential plasma samples were tested in 34 of these children. Plasma viral RNA levels ranged as high as 10(9) RNA copies/ml, and correlated with titers of infectious virus measured in mosquitoes (r= 0.69). Plasma viral RNA levels fell rapidly during the last several days of the febrile period. We did not find a significant difference in maximal plasma viral RNA levels between children with DHF and children with dengue fever, but peak viral RNA levels were identified in only 16 subjects. We conclude that this quantitative RT-PCR method will be valuable for further studies of natural DV infections