C. Leonard

Lung immunopathology in cases of sudden asthma death

The histopathology of airway inflammation in rare cases of sudden asphyxic asthma death (SAAD) is unclear. This study examines, for the first time, the relative disposition of lymphocyte and macrophage subsets and eosinophils in proximal and distal tissues of such cases. Multiple resection specimens from five cases of SAAD were studied. Tissue blocks were obtained at necroscopy and immediately frozen in liquid nitrogen within 18 hours of death (death occurring within 1 h of the onset of an unprovoked asphyxic asthma attack). After immunohistological staining, frozen sections underwent semi-quantitative analysis (cell counts per unit area) for T-cells, macrophages and eosinophils using computerized imaging systems. Subsets of T-cells and macrophages were estimated using double immunofluorescence techniques. Variability within samples, between samples and between cases was compared. These cases of fatal asthma showed infiltrates of T-cells, macrophages and eosinophils within peribronchial tissues. Distinct from stable asthma, a CD8+ T-cell dominance was found. A high proportion of eosinophils were activated (EG2+), whereas the relative proportion of antigen-presenting cells (RFD1+) did not seem to be abnormal, although numbers of these cells were high. These features were seen both in proximal and distal tissues. The variability of these parameters within an individual was 9.4-15.2%, however, the variability between individual cases was greater. Sudden asphyxic asthma is associated with inflammatory infiltrates both of proximal and distal lung tissues. In contrast to stable asthma, this infiltrate contains large numbers of CD8+ T-cells, suggesting distinct qualitative as well as quantitative characteristics in the immunopathology of sudden asthma death.

Allergen-induced CD30 expression on T cells of atopic asthmatics

Background The importance of TH2‐type T cell cytokines in atopic disease is widely accepted. CD30, a member of the TNF/NGF receptor superfamily, is expressed on a proportion of activated CD45RO+ T cells and has been proposed as a marker for TH2 phenotype. CD30 ligand‐CD30 interaction has been shown to positively influence development of the TH2 phenotype, and serum levels of soluble CD30 (sCD30) have been used as prognostic markers in HIV, SLE, Epstein‐Barr Virus infection and Hodgkins Lymphoma but not as yet in allergic disease.

T-cell cytokines may control the balance of functionally distinct macrophage populations.

As monocytes differentiate into mature macrophages, subsets emerge that exhibit stimulatory, suppressive or phagocytic potential. These functionally distinct subsets can be discriminated using monoclonal antibodies RFD1 and RFD7. As examples of all these subsets have been repeatedly identified within the macrophage pool in a variety of organs the overall functional capacity of this pool will depend on the relative balance of these subpopulations. This study investigates whether this balance present in mature macrophage populations can be regulated by the local influence of T‐cell‐derived cytokines. The dose‐dependent effect of cytokines interferon‐γ (IFN‐γ), interleukins (IL) IL‐2, IL‐4 and IL‐10 on the phenotype and function of monocyte‐derived macrophages was determined. Subsets of mature cells were quantified by identifying RFD1+ RFD7− stimulatory cells (D1+); RFD1− RFD7+ phagocytes (D7+) and RFD1+ RFD7+ suppressive cells (D1/D7+). IFN‐γ and IL‐4 increased the relative proportions of D1+ stimulatory cells and upregulated HLA‐DR expression. IFN‐γ also increased the capacity of the mature macrophage pool to stimulate T‐cell proliferation. IL‐10 reduced the proportions of D1+ stimulatory cells while promoting the differentiation of D7+ phagocytes and D1/D7+ suppressive cells. IL‐10 induced changes also reduced the functional capacity of the mature populations to stimulate T cells in auto and allogenic mixed lymphocyte reactions (MLR). IL‐2 had no effect on differentiation of monocytes. Thus IL‐4 and IFN‐γ are seen to induce the development of stimulatory macrophages while IL‐10 promotes differentiation of monocytes to mature phagocytes and suppressive macrophages. It is concluded that mature macrophage phenotype is ‘plastic’ and under the control of T‐cell‐derived mediators. Furthermore, within the differentiating monocytes, phenotypic change appears to carry with it functional change, thus retaining the relationship between antigen expression and activity in the mature macrophage populations.

Fluticasone propionate induced alterations to lung function and the immunopathology of asthma over time

BACKGROUND Inhaled corticosteroids are the most widely used treatment for asthma, a disease characterised by both functional and immunopathological abnormalities. This study investigated the relative effects of inhaled corticosteroids on these two features of asthma over time. METHODS A randomised, double blind, placebo controlled, parallel group study with inhaled fluticasone propionate, (FP 2 mg daily) was conducted in 27 patients with asthma. Following baseline analysis, the study tested the effects of short term (two weeks) and longer term (eight weeks) treatment. At each time point (0, 2, and 8 weeks) lung function tests were performed and endobronchial biopsy specimens obtained to determine the distribution and number of lymphocyte, macrophage and eosinophil subsets using immunohistological analysis. Twenty three patients completed the study, 11 on FP and 12 placebo. RESULTS FEV1, ΔFEV1, FEF25–75, and FEV1/FVC all improved after two weeks of FP treatment. This improvement was maintained but not increased after eight weeks. PC20FEV1 showed a trend to increase but was not significantly improved at eight weeks. No significant changes were seen in the placebo group. The numbers of T cells, macrophages, and eosinophils in the bronchial wall were reduced by two weeks of treatment with FP but were unaltered by placebo. The improvement offered by FP continued over the eight week period. Reductions in CD4:CD8 ratio and numbers of activated (EG2+) eosinophils were only significant after eight weeks of treatment. CONCLUSIONS These results reveal that FP influences both functional and immunopathological parameters of asthma. Temporal relationships suggest that these are parallel but not necessarily interrelated effects. While short term treatment is effective in “normalising” the functional abnormalities in asthma, the impact of FP on bronchial inflammation appears to be progressive, taking up to eight weeks and more.

Dysregulation of monocyte differentiation in asthmatic subjects is reversed by IL-10.

IL‐10 can modulate the differentiation of normal monocytes to macrophages, increasing the proportion of maturing cells with a phenotype consistent with T cell suppressive activity. Analysis of the immunopathology in endobronchial biopsies from asthmatic subjects has revealed significantly reduced proportions of suppressive macrophage populations associated with chronic T‐cell mediated inflammation.

A comparison of regular with intermittent bronchodilators in asthma patients on inhaled steroids.

The aim of this study was to compare the effect of regular versus intermittent (p.r.n.) bronchodilators on bronchial reactivity and asthma control in patients on concomitant inhaled corticosteroids. We studied 12 patients with asthma in a prospective, randomised, single-blind, single-dummy, three-period crossover trial comparing placebo (2 puffs t.d.s.), salbutamol (200μg t.d.s.) and oxitropium bromide (200μg t.d.s.) for 28 days each. Computerised spirometry and bronchial reactivity to histamine were obtained on entry and after each treatment period. Symptom scores, use of rescue bronchodilator and peak expiratory flow rates were recorded daily. There were no significant differences in bronchial hyperreactivity between the salbutamol, oxitropium and placebo treatment periods. There were no significant differences in baseline FEV1, FEF25–75%, symptom scores, use of rescue bronchodilator or morning and evening PEFR between treatment periods. Intermittent beta agonist therapy is as effective as regular therapy in terms of asthma control and bronchial hyperreactivity in patients on concomitant inhaled corticosteroid therapy. Since intermittent therapy achieves similar results with significantly lower beta agonist consumption, the data support current recommendations that beta agonists should be taken on a p.r.n. basis in asthma patients on inhaled steroids.

Utility of Wang transbronchial needle biopsy in sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown aetiology, commonly seen in the western world. The incidence varies and may be as high as 40/100,000 of the population per year. The commonest mode of presentation is as hilar and mediastinal lymphadenopathy on a chest radiograph. Even though sarcoid is in general a benign disease and most patients will not progress to chronic lung disease, a tissue diagnosis is necessary for management as other differential diagnoses such as lymphoma, tuberculosis and other causes of interstitial lung disease need to be excluded.The usual method of a obtaining a tissue diagnosis is transbronchial forceps biopsy (TBBx), via a fibre-optic bronchoscope (FOB). The presence of non-caseating granuloma in the biopsy specimen is diagnostic of sarcoidosis if the tissue is stain and culture negative for tuberculosis and fungi. However TBBx carries significant complications — in particular there is a risk of pneumothorax (10–20 per cent) and significant and rarely life-threatening haemorrhage has been reported. Furthermore, a diagnosis of sarcoidosis is made by TBBx in only approximately 70 per cent of cases. Thus in about 30 per cent of cases a further procedure such as mediastinoscopy or open lung biopsy is required to obtain a tissue diagnosis.We report a patient with suspected sarcoidosis who had negative TBBx in whom the diagnosis was confirmed using a Wang transbronchial needle (MW-319, Mill Rose Lab., U.S.A.) to biopsy mediastinal lymph nodes via the FOB.