Rigid bronchoscopy: a consultant survey.

INTRODUCTION: Inhalation of foreign bodies represents a potentially fatal emergency in both adults and children. Chest x-ray, in isolation, is neither sensitive nor specific. Rigid bronchoscopy represents the gold standard to diagnose and retrieve paediatric foreign bodies. Cases are encountered infrequently, creating anxieties about their management. Little is known about the confidence in, and maintenance of, rigid bronchoscopy skills by ear, nose and throat teams. METHODS: A 15-question survey was completed by 50 practising otolaryngology consultants in England. RESULTS: Results show that almost 40% of otolaryngology consultants covering rigid bronchoscopy have not performed bronchoscopy in more than 5 years. Consultants raised concerns about the anaesthetic support and the speed of equipment assembly. Questions on clinical practice showed disparities in practice in the same scenario. CONCLUSIONS: The authors advocate addressing many of the issues raised by the study with a greater availability of simulation courses and regular scheduled intradepartmental teaching days for all professionals involved. National guidelines on criteria for transfer to tertiary centres would improve the consistency of practice.

Chemotaxis of polymorphonuclear leukocytes from patients with rheumatoid arthritis.

Using a new in vitro method of measuring the chemotaxis of polymorphonuclear leukocytes from peripheral blood, a chemotactic index has been calculated. The mean chemotactic index of 320 in 24 patients with definite rheumatoid arthritis, was significantly less (P < 0.0005) than the mean of 555 in 24 normal controls matched for age and sex. The mean chemotactic index of 435 in eight patients with juvenile rheumatoid arthritis was also significantly less (P < 0.01) than that of 553 in similarly matched controls. The chemotactic index could not be correlated with age, sex, disease activity, drugs used in treatment, latex titer, immunoglobulin levels, or protein coating on the cells. However, there was a correlation between the chemotactic index and the serum complement B(1e)/B(1a) value (P < 0.01) in 17 patients with adult onset rheumatoid arthritis. Although the serum complement B(1e)/B(1a) values were within the normal range, the lowest chemotactic indices were associated with the lowest complement values. The chemotactic indices in three patients with severe connective tissue disease (seropositive rheumatoid arthritis, systemic lupus erythematosus, and polymyositis) returned to normal after 5 days' treatment with 60 mg of prednisolone per day. Incubation of the cells from patients with rheumatoid arthritis with hydrocortisone in vitro failed to alter the chemotactic indices. Prior incubation of normal cells with purified rheumatoid factor complexes, rheumatoid serum, or macromolecules of iron dextran impaired their chemotaxis. It is suggested that phagocytosis of complexes in vivo is a possible mechanism by which the chemotaxis of the polymorphonuclear leukocytes of patients with rheumatoid arthritis is impaired. This impairment in chemotaxis may explain the increased incidence of bacterial infection, both during life and as a cause of death in these patients.

Diversity and functions of intestinal mononuclear phagocytes.

The intestinal lamina propria (LP) contains a diverse array of mononuclear phagocyte (MNP) subsets, including conventional dendritic cells (cDC), monocytes and tissue-resident macrophages (mφ) that collectively play an essential role in mucosal homeostasis, infection and inflammation. In the current review we discuss the function of intestinal cDC and monocyte-derived MNP, highlighting how these subsets play several non-redundant roles in the regulation of intestinal immune responses. While much remains to be learnt, recent findings also underline how the various populations of MNP adapt to deal with the challenges specific to their environment. Understanding these processes should help target individual subsets for 'fine tuning' immunological responses within the intestine, a process that may be of relevance both for the treatment of inflammatory bowel disease (IBD) and for optimized vaccine design.

Tissue-specific differentiation of colonic macrophages requires TGFß receptor-mediated signaling.

Intestinal macrophages (mφ) form one of the largest populations of mφ in the body and are vital for the maintenance of gut homeostasis. They have several unique properties and are derived from local differentiation of classical Ly6Chi monocytes, but the factors driving this tissue-specific process are not understood. Here we have used global transcriptomic analysis to identify a unique homeostatic signature of mature colonic mφ that is acquired as they differentiate in the mucosa. By comparing the analogous monocyte differentiation process found in the dermis, we identify TGFß as an indispensable part of monocyte differentiation in the intestine and show that it enables mφ to adapt precisely to the requirements of their environment. Importantly, TGFßR signaling on mφ has a crucial role in regulating the accumulation of monocytes in the mucosa, via mechanisms that are distinct from those used by IL10.

TGFßR signalling controls CD103+CD11b+ dendritic cell development in the intestine.

CD103+CD11b+ dendritic cells (DCs) are unique to the intestine, but the factors governing their differentiation are unclear. Here we show that transforming growth factor receptor 1 (TGFßR1) has an indispensable, cell intrinsic role in the development of these cells. Deletion of Tgfbr1 results in markedly fewer intestinal CD103+CD11b+ DCs and a reciprocal increase in the CD103-CD11b+ dendritic cell subset. Transcriptional profiling identifies markers that define the CD103+CD11b+ DC lineage, including CD101, TREM1 and Siglec-F, and shows that the absence of CD103+CD11b+ DCs in CD11c-Cre.Tgfbr1 fl/fl mice reflects defective differentiation from CD103-CD11b+ intermediaries, rather than an isolated loss of CD103 expression. The defect in CD103+CD11b+ DCs is accompanied by reduced generation of antigen-specific, inducible FoxP3+ regulatory T cells in vitro and in vivo, and by reduced numbers of endogenous Th17 cells in the intestinal mucosa. Thus, TGFßR1-mediated signalling may explain the tissue-specific development of these unique DCs.Developmental cues for the different dendritic cell (DC) subsets in the intestine are yet to be defined. Here the authors show that TGFßR1 signalling is needed for development of CD103+CD11b+ intestinal DCs from CD103-CD11b+ cells and that they contribute to the generation of Th17 and regulatory T cells.

The lymph nodes draining the small intestine and colon are anatomically separate and immunologically distinct.

Dendritic cells (DCs) in the small intestine (SI) and colon are fundamental to direct intestinal immune responses; they migrate to the mesenteric lymph nodes (MLNs) and prime T cells. We demonstrate anatomical segregation of lymphatic drainage from the intestine, specifically that DCs from the SI and colon migrate to different nodes within the MLN, here called the sMLN and cMLN. As a consequence, different frequencies of DC subsets observed in the SI and colon are reflected among the DCs in the sMLN and cMLN. Consistent with the SI's function in absorbing food, fed antigen is presented in the sMLN, but not in the cMLN. Furthermore, the levels of expression of CCR9 and α4ß7 are increased on T cells in the sMLN compared with the cMLN. DCs from the cMLN and colon are unable to metabolize vitamin A to retinoic acid (RA); thus, DCs may contribute to the differential expression of tissue homing markers observed in the sMLN and cMLN. In summary, the sMLN and cMLN, and the DCs that migrate to these LNs are anatomically and immunologically separate. This segregation allows immune responses in the SI and colon to be controlled independently.

Colonic tolerance develops in the iliac lymph nodes and can be established independent of CD103(+) dendritic cells.

Tolerance to harmless exogenous antigens is the default immune response in the gastrointestinal tract. Although extensive studies have demonstrated the importance of the mesenteric lymph nodes (MLNs) and intestinal CD103(+) dendritic cells (DCs) in driving small intestinal tolerance to protein antigen, the structural and immunological basis of colonic tolerance remain poorly understood. We show here that the caudal and iliac lymph nodes (ILNs) are inductive sites for distal colonic immune responses and that colonic T cell-mediated tolerance induction to protein antigen is initiated in these draining lymph nodes and not in MLNs. In agreement, colonic tolerance induction was not altered by mesenteric lymphadenectomy. Despite tolerance development, CD103(+)CD11b(+) DCs, which are the major migratory DC population in the MLNs, and the tolerance-related retinoic acid-generating enzyme RALDH2 were virtually absent from the ILNs. Administration of ovalbumin (OVA) to the distal colon did increase the number of CD11c(+)MHCII(hi) migratory CD103(-)CD11b(+) and CD103(+)CD11b(-) DCs in the ILNs. Strikingly, colonic tolerance was intact in Batf3-deficient mice specifically lacking CD103(+)CD11b(-) DCs, suggesting that CD103(-) DCs in the ILNs are sufficient to drive tolerance induction after protein antigen encounter in the distal colon. Altogether, we identify different inductive sites for small intestinal and colonic T-cell responses and reveal that distinct cellular mechanisms are operative to maintain tolerance at these sites.

Mechanisms of oral tolerance.

Oral tolerance is the specific immunological unresponsiveness induced by feeding antigen. Although it is an obstacle to oral vaccination, it is probably the mechanism that prevents intestinal hypersensitivity reactions to food antigens and may provide a novel strategy for the treatment of a range of inflammatory disorders. Feeding antigen can provide stable and long-lasting tolerance of a wide range of immune responses to a variety of antigens. However, the mechanisms of oral tolerance and the major factors that influence them remain controversial.

CCR2(+)CD103(-) intestinal dendritic cells develop from DC-committed precursors and induce interleukin-17 production by T cells.

The identification of intestinal macrophages (mφs) and dendritic cells (DCs) is a matter of intense debate. Although CD103(+) mononuclear phagocytes (MPs) appear to be genuine DCs, the nature and origins of CD103(-) MPs remain controversial. We show here that intestinal CD103(-)CD11b(+) MPs can be separated clearly into DCs and mφs based on phenotype, gene profile, and kinetics. CD64(-)CD103(-)CD11b(+) MPs are classical DCs, being derived from Flt3 ligand-dependent, DC-committed precursors, not Ly6C(hi) monocytes. Surprisingly, a significant proportion of these CD103(-)CD11b(+) DCs express CCR2 and there is a selective decrease in CD103(-)CD11b(+) DCs in mice lacking this chemokine receptor. CCR2(+)CD103(-) DCs are present in both the murine and human intestine, drive interleukin (IL)-17a production by T cells in vitro, and show constitutive expression of IL-12/IL-23p40. These data highlight the heterogeneity of intestinal DCs and reveal a bona fide population of CCR2(+) DCs that is involved in priming mucosal T helper type 17 (Th17) responses.

Lymph-borne CD8α+ dendritic cells are uniquely able to cross-prime CD8+ T cells with antigen acquired from intestinal epithelial cells.

Cross-presentation of cellular antigens is crucial for priming CD8(+) T cells, and generating immunity to intracellular pathogens--particularly viruses. It is unclear which intestinal phagocytes perform this function in vivo. To address this, we examined dendritic cells (DCs) from the intestinal lymph of IFABP-tOVA 232-4 mice, which express ovalbumin in small intestinal epithelial cells (IECs). Among lymph DCs (LDCs) only CD103(+) CD11b(-) CD8α(+) DCs cross-present IEC-derived ovalbumin to CD8(+) OT-I T cells. Similarly, in the mesenteric lymph nodes (MLNs), cross-presentation of IEC-ovalbumin was limited to the CD11c(+) MHCII(hi) CD8α(+) migratory DCs, but absent from all other subsets, including the resident CD8α(hi) DCs. Crucially, delivery of purified CD8α(+) LDCs, but not other LDC subsets, into the MLN subcapsular lymphatic sinus induced proliferation of ovalbumin-specific, gut-tropic CD8(+) T cells in vivo. Finally, in 232-4 mice treated with R848, CD8α(+) LDCs were uniquely able to cross-prime interferon γ-producing CD8(+) T cells and drive their migration to the intestine. Our results clearly demonstrate that migrating CD8α(+) intestinal DCs are indispensable for cross-presentation of cellular antigens and, in conditions of inflammation, for the initial differentiation of effector CD8(+) T cells. They may therefore represent an important target for the development of antiviral vaccinations.

Orthotopic liver transplantation reverses the adverse nutritional changes of end-stage liver disease in children.

The changes in growth and body composition after orthotopic liver transplantation (OLT) were studied in 61 children [median age at OLT 3.49 y (range: 0.04-14.5 y), 26 boys and 35 girls] who had survived > or = 1 y post-OLT. Height, weight, midarm circumference (MAC), triceps skinfold thickness (TSF), and subscapular skinfold thickness (SSF) were measured at OLT, 3 and 6 mo later, then annually up to 5 y. SD scores (SDS) were derived from population standards. Results are reported as mean SDS +/- SEM. At OLT the children were short and malnourished (height: -0.98 +/- 0.22; weight -0.82 +/- 0.18; MAC: -1.77 +/- 0.21; TSF: -1.27 +/- 0.17; SSF: -1.49 +/- 0.17). By 3 mo post-OLT, there was a sustained improvement in MAC (-0.73 +/- 0.22), TSF (-0.48 +/- 0.18), and SSF (-0.50 +/- 0.18). Weight SDS (-0.48 +/- 0.20) improved by 6 mo without significant change in height SDS. The three children with Alagille syndrome were smaller (height, weight, and MAC) than children with other diagnoses but did show catch-up growth. Fulminant hepatic failure was not associated with growth failure before or after OLT. Infants (n = 14) were smaller and more malnourished at OLT (smaller skinfold thicknesses and lower weight SDS) than those who received transplants at an older age. By 1 y post-OLT, the only persisting difference was in TSF. Abnormal liver function at 1 y post-OLT (n = 8) and repeated episodes of steroid-treated rejection (n = 13) were associated with worsening height and weight SDS. The use of tacrolimus for graft salvage from rejection (n = 6) was not associated with growth failure. In conclusion, end-stage liver disease has a more adverse effect on MAC, TSF, and SSF than on height and weight, but a marked and rapid improvement occurred post-OLT. Children who were most severely malnourished and growth restricted at the time of OLT showed the greatest catch-up growth after OLT.

Chemotherapy effects on hepatoblastoma. A histological study.

The histopathological features of hepatoblastoma in 17 patients treated with preoperative chemotherapy were compared with those in 11 patients not subjected to chemotherapy during the same 11-year period. Tumor necrosis was more extensive in patients receiving preoperative chemotherapy. Two tumors, however, were apparently unaffected by chemotherapy. There was no obvious correlation between the extent of necrosis and the number of courses of chemotherapy. There also seems to be no evidence of preferential ablation of a particular morphological type of tumor. The most notable feature in cases treated with chemotherapy was the extensive presence of osteoid. Osteoid was present in 36% of untreated cases, occupying < 5% of the surface area, compared with 82% in the treated group. In seven cases, osteoid occupied > 40% of the surface area. This finding raises speculation about the role of chemotherapy in the maturation of tumors that have an inherent ability to differentiate. A long-term study is needed to clarify the prognostic significance of mature heterologous elements in hepatoblastoma.

Evidence that Ia+ bone-marrow-derived cells are the stimulus for the intestinal phase of the murine graft-versus-host reaction.

We have investigated whether bone marrow (BM) or tissue-derived cells provide the stimulus for the intestinal phase of graft-versus-host reaction (GVHR) in F1 mice injected with parental spleen cells. After injection of CBA cells, the characteristic increases in crypt length, crypt cell production rate (CCPR), and intraepithelial lymphocyte (IEL) count occurred in the jejunum of (CBA x BALB/c)F1----CBA BM chimeras, but not in CBA----(CBA x BALB/c)F1 BM chimeras. Thus, BM-derived cells alone can induce intestinal GVHR and, as similar intestinal alterations were found in (A.TH x A.TL)----A.TL BM chimeric mice after injection of A.TL spleen cells, we deduce that the BM-derived stimulator cells are Ia+. We conclude that the intestinal pathology in this model of GVHR is an indirect effect of soluble mediators that are released during a local delayed-type hypersensitivity (DTH) reaction induced by recognition of Ia+ passenger leukocytes within the mucosa.

Hypersensitivity reactions in the small intestine. 6. Pathogenesis of the graft-versus-host reaction in the small intestinal mucosa of the mouse.

The intestinal phase of the graft-versus-host reaction (GVHR) has been investigated in adult F1 mice bearing grafts of fetal gut using an H-2-incompatible and an H-2-compatible, Mls-incompatible combination. The results indicate that the mitotic activity of the intestinal crypts and the number of intraepithelial lymphocytes are sensitive parameters of the mucosal cell-mediated immune response in the GVHR. Using these indices, indirect evidence has been obtained that soluble factors may be responsible for the damage to the intestine in the GVHR. Possible pathways of lymphocyte activation and migration to the gut are proposed to explain the role of gut-associated T cells in the production of these mediators.

Induction of intestinal graft-versus-host reactions across mutant major histocompatibility antigens by T lymphocyte subsets in mice.

We have examined the ability of highly purified subsets of C57B1/6 L3T4+ and Lyt2+ cells to cause intestinal graft-versus-host reactions in H-2 mutant mice expressing isolated class I (bm1) or II (bm12) MHC mutations. Heavily irradiated B6xbm12)F1 mice given B6 L3T4+ T cells (anti-class II GVHR) developed an acute, lethal GVHR that was associated with intense jejunal crypt hyperplasia and an early rise in the density of intraepithelial lymphocytes. Irradiated (B6xbm1)F1 mice given B6 Lyt2+ T cells (anti-class I GVHR) showed a similar phase of crypt hyperplasia within the first 2 weeks, but this was less marked than for anti-class II GVHR and was not associated with an increase in IEL count. Only very minor gut pathology was observed when B6 Lyt2+ T cells were transferred to irradiated mice carrying the bm9 class I mutation, which is much weaker than the bm1 mutation and does not stimulate Lyt2+ helper T cells. The GVHR mediated by B6 L3T4+ and Lyt2+ T cells was H-2 class-specific, as no pathology was seen in bm12 recipients of Lyt2+ cells or in bm1 recipients of L3T4+ cells. B6 L3T4+ and Lyt2+ T cells both induced splenomegaly and intestinal GVHR in nonirradiated, 4-5-day-old neonatal (B6xbm12)F1 or (B6xbm1)F1 mice, respectively, a form of intestinal GVHR that does not require specific cytotoxic T lymphocytes. Again, Lyt2+ T cells were less efficient than L3T4+ T cells in the induction of GVHR. Thus, both class I and class II MHC-restricted T cells can mediate different forms of intestinal GVHR under appropriate circumstances, but class II MHC-restricted T cells may be more efficient.

Hypersensitivity reactions in the small intestine. VII. Induction of the intestinal phase of murine graft-versus-host-reaction by Lyt 2- T cells activated by I-A alloantigens.

This study has examined the nature of the T lymphocytes and the alloantigens that induce the intestinal phase of graft-versus-host reaction in unirradiated F1 mice. Parental spleen cells were depleted of T cells subsets by treatment with anti-Lyt monoclonal antibodies and complement, and we show that Lyt 2- cells alone induce the increased lymphocytic infiltration of the epithelium that characterizes the intestinal graft-versus-host reaction. Lyt 2- cells are also required to induce some of the associated crypt hyperplasia, but the full crypt changes require both Lyt 2- and Lyt 2+ T cells. In intra-H-2 recombinant congenic F1 mice with graft-versus-host reaction, a disparity at the I-A locus was alone sufficient and necessary for crypt hyperplasia and increased intraepithelial lymphocyte counts, while an I-J incompatibility led to suppression of both these indices. The results support the hypothesis that the intestinal pathology of acute GVHD is induced by class II MHC-restricted delayed-type hypersensitivity effector T cells.

Augmentation of intestinal and peripheral natural killer cell activity during the graft-versus-host reaction in mice.

We have investigated the possibility that nonspecific cytotoxicity may be involved in the pathogenesis of the intestinal phase of the graft-versus-host reaction (GVHR) in mice. A GVHR was induced in unirradiated (CBA X BALB/c)F1 mice and natural killer (NK) cell activity against YAC-1 followed in the spleen, mesenteric lymph node (MLN), and isolated intraepithelial lymphocytes (IEL). Augmented NK activity developed simultaneously in all tissues in parallel with the progress of the GVHR. The NK activity of IEL also showed a close association with the increased numbers of IEL found on sections of small intestine. Mature T lymphocytes and macrophages did not contribute to the nonspecific cytotoxicity, and antihost cytotoxic T cells were not detected in any tissue. The results indicate that generalized recruitment of NK cells occurs during the GVHR both in peripheral and intestinal lymphoid tissues, and we propose that lymphokines are responsible for this phenomenon. NK cells recruited by a delayed-type hypersensitivity reaction may contribute to the pathogenesis of the GVHR, but an alternative explanation is that NK cells may inhibit the progression of the GVHR.

Hepatic artery thrombosis after liver transplantation in children under 5 years of age.

The incidence of hepatic artery thrombosis (HAT) following orthotopic liver transplantation in children varies from 4% to 26% and represents a significant cause of graft loss. The purpose of this study was to analyze the risk factors for HAT following liver transplantation in children less than 5 years old. Seventy-three transplants were performed in 62 children under 5 years of age, including 16 for acute hepatic failure, 46 for chronic liver disease, and 11 retransplants. Twenty-four whole liver grafts (WLG) and 49 reduced size grafts (3 right lobes, 16 left lobes, and 30 left lateral segments) were transplanted. The recipient common hepatic artery was used to provide arterial inflow in 22 transplants and an infrarenal iliac conduit in 51 transplants. The overall incidence of HAT was 8 out of 73 transplants (11%). The cold ischemia time (14.3 +/- 3.03 hr) in this group was significantly longer than the cold ischemia time for those without HAT (11.7 +/- 3.94 hr) (P = 0.049). The incidence of HAT for whole and reduced grafts was 25% (6/24) and 4% (2/49), respectively (P = 0.01). HAT occurred in 6 of 22 grafts (27.3%) revascularized from the recipient common hepatic artery, compared with 2 of 51 grafts (3.9%) using an infrarenal arterial conduit (P = 0.008). The combination of recipient hepatic arterial inflow to a WLG resulted in HAT in 50% (6/12), whereas there were no cases of HAT with an iliac conduit to a WLG (P = 0.01). Of the eight patients with HAT, five are alive (median follow-up, 20 months; range, 7-27 months). Five patients were retransplanted, three within the first 2 weeks and two at 4 and 5 months for abnormal liver function in association with clinical and histological features of chronic rejection. Prolonged cold ischemia time and use of a whole graft with recipient hepatic arterial inflow are risk factors for developing HAT. The use of reduced size grafts and infrarenal iliac arterial conduits are associated with a low incidence of HAT.

Liver transplantation for Langerhans' cell histiocytosis--a case report and literature review.

Langerhans' cell histiocytosis (LCH) is a rare disorder of unknown etiology and pathogenesis. End-stage chronic liver disease is one presentation and orthotopic liver transplantation (OLT) has been reported in 17 cases, with variable resolution of LCH lesions postoperatively. We report a case of multisystem LCH with end-stage liver disease treated by OLT and review the overall results of OLT for children with LCH.