The Diagnostics and Management of Bronchopulmonary Sequestration: An International Survey among Specialized Caregivers.

BACKGROUND: Our objective was to explore the treatment preferences for bronchopulmonary sequestration (BPS) among an international group of specialized caregivers. METHODS: Sixty-three participants from 17 countries completed an online survey concerning the diagnostics, treatment, and follow-up. Recruitment took place among members of the Collaborative Neonatal Network for the first European Congenital Pulmonary Airway Malformation Trial Consortium and through the Association for European Pediatric and Congenital Cardiology working group database. RESULTS: Most of the 63 participants were pediatric surgeons (52%), followed by pediatric pulmonologists (22%), and pediatric cardiologists (19%). The majority (65%) treated more than five cases per year and 52% standardly discussed treatment in a multidisciplinary team. Half of the participants (52%) based the management on the presence of symptoms, versus 32% on the intralobar or extralobar lesion localization. Centers with both surgical and interventional cardiac/radiological facilities (85%) preferred resection to embolization in symptomatic cases (62 vs. 15%). In asymptomatic cases too, resection was preferred over embolization (38 vs. 9%); 32% preferred noninterventional treatment, while 11% varied in preference. These treatment preferences were significantly different between surgeons and nonsurgeons (p < 0.05). Little agreement was observed in the preferred timing of intervention as also for the duration of follow-up. CONCLUSIONS: This survey demonstrates a variation in management strategies of BPS, reflecting different specialist expertise. Most centers treat only a handful of cases per year and follow-up is not standardized. Therefore, management discussion within a multidisciplinary team is recommended. Recording patient data in an international registry for the comparison of management strategies and outcomes could support the development of future guidelines. LEVEL OF EVIDENCE: Level IV.

Oligoclonality of Vdelta1 and Vdelta2 cells in human peripheral blood mononuclear cells: TCR selection is not altered by stimulation with gram-negative bacteria.

Despite the enormous potential repertoire of gammadelta T cells, there are several observations which suggest that the expressed gammadelta repertoire in the periphery of normal individuals is often quite restricted. To assess selective expansions among gammadelta T cells from both adult and newborn blood samples, PBMC from 12 normal adults and cord blood from 15 normal newborns were analyzed for TCRDV1 and TCRDV2 junctional diversity by CDR3 size spectratyping and single-strand conformational polymorphism. Although TCRBV usage showed extensive heterogeneity in adults and newborns, both populations often showed CDR3 region restriction for TCRDV1 and TCRDV2. Analysis of the CDR3 spectratype patterns of newborn twins suggested that clonal selection for TCRDV is independent of genetic background. The possible role of Gram-negative bacteria in driving selective responsiveness of gammadelta T cells in PBMCs from adults was examined by in vitro stimulation with Escherichia coli and Pseudomonas aeruginosa. Donors whose TCRDV repertoire was highly clonal in the unstimulated blood cells showed the same predominant clones among the bacteria-stimulated cultures. In individuals whose gammadelta T cells were less restricted, in vitro stimulation did not select for clonality; rather, the TCRDV repertoires were similar before and after bacterial stimulation. Together, these data indicate that gammadelta T cells are often clonally restricted in adults as well as in newborns and suggest that the prominent stimulatory activity of Gram-negative bacteria does not by itself account for the restriction or diversity of the gammadelta T cell repertoire.

Escherichia coli and Pseudomonas aeruginosa induce expansion of V delta 2 cells in adult peripheral blood, but of V delta 1 cells in cord blood.

Human peripheral blood T cells proliferate in response to Escherichia coli and Pseudomonas aeruginosa. We observed that during the first few days after stimulation a large percentage of the responding PBMC were gamma delta T cells. In our study we characterized the early T cell responses of freshly isolated adult and newborn PBMC to soluble preparations of heat-killed E. coli and P. aeruginosa. Specimens from all healthy adults tested showed intense proliferation in response to both bacterial preparations; at 6 days, the responding cells were mainly T cell blasts, of which high percentages (up to 80%) were gamma delta T cells, most expressing V delta 2/V gamma 9. All newborn blood specimens tested also showed T cell proliferative responses, which included a marked expansion of gamma delta T cells, mainly of the V delta 1 subset. Populations of purified V delta 1 and V delta 2 T cells were obtained from adult PBMC following stimulation with E. coli; both subsets proliferated upon rechallenge with the bacterial preparations. Protease treatment of the bacterial preparations did not appreciably affect their ability to induce expansion of gamma delta T cells in either adult or cord blood, indicating that the stimulatory components were not proteins. The response of gamma delta T cells from newborns indicates that prior exposure to bacterial products is not necessary and suggests that gamma delta T cells are important elements in natural immunity to these extracellular organisms.

Responses of human T cells to dominant discrete protein antigens of Escherichia coli and Pseudomonas aeruginosa.

Normal human beings have circulating T lymphocytes that proliferate in response to Escherichia coli and Pseudomonas aeruginosa. We performed the present study to characterize the nature of the responding T cells and to determine whether distinct or shared conventional antigens, superantigens or polyclonal activators account for T cell proliferation. Long term antigen-specific T cell lines were generated by repeated stimulation of PBMC from four donors with soluble antigen preparations of E. coli or P. aeruginosa. This resulted in the emergence of distinct T cell populations, which responded to strains of either E. coli or P. aeruginosa, but not to both. Trypsin treatment of the bacterial preparations largely eliminated their ability to stimulate the T cells. The T cell lines were predominantly CD4+ and their proliferation to bacterial antigens was optimal using autologous APC. E. coli T cell lines proliferated not only in response to the E. coli strain with which they were initially selected, but also to four different strains of E. coli, as well as to several related Gram-negative species. P. aeruginosa selected T cells exhibited proliferative responses to six different P. aeruginosa strains, but not to the other Gram-negative species. The finding that repeated stimulation of PBMC with E. coli or P. aeruginosa leads to CD4+ T cells highly reactive with conventional protein antigens specific either for E. coli or P. aeruginosa indicates that these bacteria possess separate dominant protein antigens that drive the proliferation of peripheral blood T cells.

T lymphocyte responses to antigens of gram-negative bacteria in pyelonephritis.

We showed previously that large numbers of T lymphocytes accumulate within a few days in the kidneys of rats with ascending pyelonephritis induced with Escherichia coli or Pseudomonas aeruginosa. CD4+ T cells propagated from the lesions exhibited MHC-restricted proliferative responses to formalin-fixed bacteria of the species used to induce infection. In the present study we investigated further the nature of the antigens responsible for the T cell proliferation and studied the ability of different bacterial strains and species to produce proliferative responses. We found that heat-killed bacteria were more stimulatory than formalin-fixed bacteria, and that soluble supernatants of heat-killed organism were also effective. The stimulatory effects of supernatants were destroyed by trypsin and the responses were MHC-restricted. Twelve different E. coli strains, with or without characteristics of uropathogenicity in humans, were all highly stimulatory to T cells derived from a kidney infected with a single E. coli strain. Strains of Klebsiella pneumoniae, Enterobacter aerogenes, and Serratia marcescens--species of Enterobacteriaceae closely related to E. coli--were also stimulatory, whereas more distantly related bacteria--Proteus, Morganella, and P. aeruginosa--were not. T cells propagated from kidneys infected with P. aeruginosa responded to supernatants of this organism, but not to E. coli supernatants. We conclude that a protein antigen (or antigens) shared by strains of E. coli and related Enterobacteriaceae, but not by other gram-negative bacteria, produce MHC-restricted proliferative responses of CD4+ T cells that infiltrate rat kidneys infected with E. coli.