Cytotoxic T lymphocytes raised against a subdominant epitope offered as a synthetic peptide eradicate human papillomavirus type 16-induced tumors

Previously, we have shown that immunization with human papillomavirus (HPV) type 16-derived cytotoxic T lymphocyte (CTL) epitope E7 49–57 (RAHYNIVTF) renders C57BL/6 mice insensitive to tumors formed by HPV16-transformed cells. In this study, we provide evidence that E7 49–57 is expressed as a subdominant CTL epitope on HPV16-transformed C57BL/6 cells. Using acid peptide elution, it is shown that HPV16-transformed cells express another CTL epitope, besides E7 49-57, which appears to be dominant. We demonstrate that a CTL line raised against the subdominant CTL epitope, offered as synthetic peptide E7 49–57, eradicates established HPV16-induced tumors in mice. Our data show that synthetic peptide-induced CTL can be applied successfully in vivo against (virus-induced) tumor, and emphasize that subdominant CTL epitopes are useful targets for immunotherapy. Furthermore, it is illustrated for the first time that HPV16-specific CTL interfere directly with HPV16-induced tumors.     

Nosocomial spread of a Staphylococcus capitis strain with heteroresistance to vancomycin in a neonatal intensive care unit

A premature infant in a neonatal intensive care unit (NICU) developed a bloodstream infection caused by coagulase-negative staphylococci (CoNS) sensitive to vancomycin. The infection persisted for 3 weeks, despite therapy with vancomycin and replacement of all intravenous catheters. The neonate died due to necrotizing enterocolitis which developed during the ongoing sepsis. We screened this strain and 216 other strains of CoNS from cultures of blood obtained from neonates between 1997 and 2000 for heteroresistance to vancomycin. Forty-eight isolates, including the strain that caused ongoing sepsis, proved heteroresistant. All isolates were identified as Staphylococcus capitis and were identical, just as their resistant stable subcolonies were, when they were genetically fingerprinted by amplified-fragment length polymorphism analysis. The heteroresistant phenotype of this endemic strain was confirmed by population analysis. We conclude that heteroresistance to vancomycin occurs in S. capitis and might be the cause of therapeutic failures in NICUs. Moreover, heteroresistant strains can become endemic in such units.     

Maturation of dendritic cells is a prerequisite for inducing immune responses in advanced melanoma patients.

PURPOSE: We have investigated the capacity of immature and mature monocyte-derived DCs pulsed with melanoma-associated peptides (gp100 and tyrosinase) to induce a primary cytotoxic T-lymphocyte response in vivo. EXPERIMENTAL DESIGN: Advanced HLA-A2.1(+) melanoma patients were vaccinated with peptide- and keyhole limpet hemocyanin (KLH)-pulsed DCs, either immature (9 patients) or matured by monocyte-conditioned medium/tumor necrosis factor alpha/prostaglandin E(2) (10 patients). RESULTS: All patients vaccinated with mature DCs showed a pronounced proliferative T-cell and humoral response against KLH. By contrast, KLH responses were absent in most of the patients vaccinated with immature DCs. Delayed-type hypersensitivity (DTH) reactions against antigen-pulsed DCs were only observed in patients vaccinated with mature DCs and not in patients vaccinated with immature DCs. MHC-peptide tetramer staining of DTH-derived T cells revealed the presence of specific T cells recognizing the melanoma-associated peptides in 1 patient. In a second patient, DTH-derived T cells showed specific lysis of tumor cells expressing the antigens used for DC pulsing. Only patients vaccinated with mature DCs showed objective clinical responses. Interestingly, both patients with long-term progression-free survival (22 and >40 months) were both vaccinated with mature DCs and demonstrated antigen-specific T-cell reactivity of DTH-derived T cells. CONCLUSIONS: We conclude that mature DC are superior to immature DC in the induction of immunological responses in melanoma patients, which may translate into improved clinical results.     

Lung and renal uptake of technetium Tc 99m sulphur colloid related to disseminated intravascular coagulation

In addition to a recently published case study, we present another three cases in which we observed both lung and renal uptake of technetium Tc 99m sulphur colloid which was related to a period of disseminated intravascular coagulation. Being familiar with this relationship may influence the diagnosis and course of the illness in certain patients.     

Effect of bacterial products on neutrophil migration in vitro.

Chronic bronchial inflammation is associated with migration of large numbers of granulocytes into the bronchial tree. A study was designed to find out whether products of bacteria commonly isolated in chronic bronchial infection stimulate neutrophil migration in vitro. Neutrophils from healthy donors were studied by a modified Boyden chamber technique. Bacterial culture filtrates stimulated neutrophil migration over a wide dilution range and the chemotactic activity was heat stable. Culture filtrates derived from Pseudomonas aeruginosa, Streptococcus pneumoniae, and Haemophilus influenzae were significantly chemokinetic and directionally chemotactic, whereas filtrates from Staphylococcus aureus were only chemotactic. Gel filtration of S aureus and P aeruginosa culture filtrates yielded high, medium, and low molecular weight fractions showing chemotactic activity. S pneumoniae and H influenzae yielded fractions with only low molecular weight chemotactic activity. Neutrophil chemotactic responses, occurring in response to all bacterial species tested, appear to represent a defence mechanism by the host. Chemoattractant activity may, however, contribute to bronchial damage mediated by products released from continuously attracted, activated neutrophils.     

A randomized controlled trial of enteral glutamine supplementation in very low birth weight infants: plasma amino acid concentrations

OBJECTIVE: Glutamine depletion has negative effects on the functional integrity of the gut and leads to immunosuppression. Very low birth weight (VLBW) infants are susceptible to glutamine depletion, as enteral nutrition is limited in the first weeks of life. Enteral glutamine supplementation may have a positive effect on feeding tolerance, infectious morbidity and short-term outcome. The aim of the study was to determine the effect of enteral glutamine supplementation on plasma amino acid concentrations, reflecting one aspect of safety of enteral glutamine supplementation in VLBW infants. METHODS: In a double-blind placebo-controlled randomized controlled trial, VLBW infants (gestational age <32 weeks or birth weight <1500 g) received enteral glutamine supplementation (0.3 g/kg per day) or isonitrogenous placebo supplementation (alanine) between day 3 and day 30 of life. Supplementation was added to breast milk or to preterm formula. Plasma amino acid concentrations were measured at four time points: before the start of the study and at days 7, 14 and 30 of life. RESULTS: Baseline patient and nutritional characteristics were not different in glutamine (n = 52) and control (n = 50) groups. Plasma concentrations of most essential and non-essential amino acids increased throughout the study period. There was no effect of enteral glutamine supplementation. In particular, the increase of plasma glutamine and glutamate concentrations was not different between the treatment groups (P = 0.49 and P = 0.34 respectively, day 30). CONCLUSIONS: Enteral glutamine supplementation in VLBW infants does not alter plasma concentrations of glutamine, glutamate or other amino acids. Enteral supplementation in a dose of 0.3 g/kg per day seems safe in VLBW infants.     

Glutamine-enriched enteral nutrition in very low birth weight infants. Design of a double-blind randomised controlled trial [ISRCTN73254583]

Background

Enteral feeding of very low birth weight (VLBW) infants is a challenge, since metabolic demands are high and administration of enteral nutrition is limited by immaturity of the gastrointestinal tract. The amino acid glutamine plays an important role in maintaining functional integrity of the gut. In addition, glutamine is utilised at a high rate by cells of the immune system. In critically ill patients, glutamine is considered a conditionally essential amino acid. VLBW infants may be especially susceptible to glutamine depletion as nutritional supply of glutamine is limited in the first weeks after birth. Glutamine depletion has negative effects on functional integrity of the gut and leads to immunosuppression. This double-blind randomised controlled trial is designed to investigate the effect of glutamine-enriched enteral nutrition on feeding tolerance, infectious morbidity and short-term outcome in VLBW infants. Furthermore, an attempt is made to elucidate the role of glutamine in postnatal adaptation of the gut and modulation of the immune response.

Methods

VLBW infants (gestational age <32 weeks and/or birth weight <1500 g) are randomly allocated to receive enteral glutamine supplementation (0.3 g/kg/day) or isonitrogenous placebo supplementation between day 3 and 30 of life. Primary outcome is time to full enteral feeding (defined as a feeding volume ≥ 120 mL/kg/day). Furthermore, incidence of serious infections and short-term outcome are evaluated. The effect of glutamine on postnatal adaptation of the gut is investigated by measuring intestinal permeability and determining faecal microflora. The role of glutamine in modulation of the immune response is investigated by determining plasma Th1/Th2 cytokine concentrations following in vitro whole blood stimulation.