Henk M. Jansen

Poor biologic activity of cross-reactive IgE directed to carbohydrate determinants of glycoproteins

BACKGROUND In our outpatient population, approximately one third of patients sensitized to grass pollen were found to have significant serum levels of anti-peanut IgE in the RAST, without positive peanut skin prick test (SPT) response and without peanut-related allergic symptoms. It was suggested earlier that poor biologic activity of IgE antibodies directed to cross-reactive carbohydrate determinants (CCD) of glycoproteins might explain these discrepancies. OBJECTIVE In this study we investigated the biologic activity of IgE directed to CCD. METHODS Sera of 32 patients allergic to grass pollen with significant levels of anti-peanut IgE, a negative response on peanut SPT, and no symptoms of peanut allergy were tested for the presence of anti-CCD IgE. Eleven of these patients with greater than 3.0 IU/ml anti-peanut IgE (patients 1 to 11) were selected together with four control patients allergic to peanut, on the basis of a positive response on peanut SPT and a history of peanut allergy (patients 12 to 15). Inhibition of the peanut RAST was performed by using proteinase K-treated grass pollen extract as a CCD source. Basophil histamine release assays (BHRAs) were performed with peanut extract and the isolated peanut major allergens Ara h 1 and Ara h 2. In addition, intracutaneous tests with peanut extract were performed. RESULTS In 29 (91%) of 32 patients with discrepant peanut RAST and SPT responses, anti-CCD IgE (> or =0.1 IU/ml) was detected. In patients 1 to 11 almost complete inhibition of the peanut RAST with CCD was found (94.3% +/- 5.5%; mean +/- SD). In contrast, in the patients allergic to peanut only partial inhibition (59%) was found in one subject (p = 0.002, Mann-Whitney test). In the BHRAs and the intracutaneous tests of patients with discrepant peanut RAST and SPT results, reactivity was found only at high concentrations of peanut allergens. When related to specific IgE levels, reactivity to peanut allergens in the BHRAs of these patients was found to be at least a factor of 1000 less when compared with reactivity to control inhalant allergens. CONCLUSION We conclude that cross-reactive IgE directed to carbohydrate determinants of glycoproteins, as found in grass pollen-sensitized patients, has poor biologic activity. It can therefore cause positive RAST results without apparent clinical significance.

IL-10 Is an Important Mediator of the Enhanced Susceptibility to Pneumococcal Pneumonia after Influenza Infection

Secondary pneumococcal pneumonia is a serious complication during and shortly after influenza infection. We established a mouse model to study postinfluenza pneumococcal pneumonia and evaluated the role of IL-10 in host defense against Streptococcus pneumoniae after recovery from influenza infection. C57BL/6 mice were intranasally inoculated with 10 median tissue culture infective doses of influenza A (A/PR/8/34) or PBS (control) on day 0. By day 14 mice had regained their normal body weight and had cleared influenza virus from the lungs, as determined by real-time quantitative PCR. On day 14 after viral infection, mice received 104 CFU of S. pneumoniae (serotype 3) intranasally. Mice recovered from influenza infection were highly susceptible to subsequent pneumococcal pneumonia, as reflected by a 100% lethality on day 3 after bacterial infection, whereas control mice showed 17% lethality on day 3 and 83% lethality on day 6 after pneumococcal infection. Furthermore, 1000-fold higher bacterial counts at 48 h after infection with S. pneumoniae and, particularly, 50-fold higher pulmonary levels of IL-10 were observed in influenza-recovered mice than in control mice. Treatment with an anti-IL-10 mAb 1 h before bacterial inoculation resulted in reduced bacterial outgrowth and markedly reduced lethality during secondary bacterial pneumonia compared with those in IgG1 control mice. In conclusion, mild self-limiting influenza A infection renders normal immunocompetent mice highly susceptible to pneumococcal pneumonia. This increased susceptibility to secondary bacterial pneumonia is at least in part caused by excessive IL-10 production and reduced neutrophil function in the lungs.

Functional subsets of allergen-reactive human CD4+ T cells

After a period of resistance, the concept of human helper T (TH)-cell subsets is gaining currency. This is the result of analyses from a number of laboratories on the cytokine profiles of T-cell clones prepared from chronically-infected and hypersensitive individuals. Here, Martien Kapsenberg and colleagues summarize these studies and speculate on the significance of skewed TH1 and TH2 responses.

Selective accumulation of differentiated CD8+T cells specific for respiratory viruses in the human lung

The lungs are frequently challenged by viruses, and resident CD8+ T cells likely contribute to the surveillance of these pathogens. To obtain insight into local T cell immunity to respiratory viruses in humans, we determined the specificity, phenotype, and function of lung-residing CD8+ T cells and peripheral blood CD8+ T cells in a paired analysis. The lung contained markedly higher frequencies of influenza (FLU)-specific and respiratory syncytial virus (RSV)-specific CD8+ T cells when compared with the circulation. This contrasted with an equal distribution of cytomegalovirus- and Epstein-Bar virus–specific CD8+ T cells. Noticeably, a substantial fraction of the lung-residing FLU- and RSV-specific CD8+ T cells had progressed to a relatively late differentiation phenotype, reflected by low expression of CD28 and CD27. Lung-derived FLU-specific CD8+ T cells had low activation requirements, as expansion of these cells could be initiated by cognate peptide in the absence of helper cell–derived signals. Thus, the human lung contains high numbers of differentiated FLU- and RSV-specific memory CD8+ T cells that can readily expand upon reexposure to virus. Resident lung T cells may provide immediate immunological protection against pulmonary virus infections.

Interleukin-8 in airway inflammation in patients with asthma and chronic obstructive pulmonary disease

We have investigated whether IL-8 is present in airway secretions from patients with asthma and chronic obstructive pulmonary disease (COPD) to obtain information on its possible role in airway inflammation in obstructive airways disease. In the bronchoalveolar lavage fluid (BALF) from 11 clinically stable patients with asthma the levels of IL-8 were increased compared to 10 healthy subjects (median: controls 21.5 pg/ml, asthma 244 pg/ml: p < 0.005). In the patients with asthma the levels of IL-8 correlated with the percentage neutrophils in the BALF (r = 0.81; p < 0.001) and with a parameter of the permeability of the respiratory membrane, the quotient (alpha 2-macroglobulin in BALF)/(alpha 2-macroglobulin in serum) (r = 0.66; p < 0.025). In the sputum sol phase of 9 patients with symptomatic asthma the levels of IL-8 were lower than in 9 patients with COPD (asthma: 6.4 ng/ml; COPD: 16.3 ng/ml; p < 0.02) and significantly correlated with those of neutrophilic myeloperoxidase (MPO; r = 0.85; p < 0.005). The increased levels of IL-8 in the airway secretions from both patients with asthma and COPD may be markers of an ongoing inflammatory process, which is more pronounced in patients with COPD. In patients with asthma the strong correlation between the levels of IL-8 and the percentage neutrophils and/or the levels of MPO points to a role of IL-8 in the recruitment and activation of neutrophils in the airway lumen.

Comparison between pathogen directed antibiotic treatment and empirical broad spectrum antibiotic treatment in patients with community acquired pneumonia: a prospective randomised study

Background: There is much controversy about the ideal approach to the management of community acquired pneumonia (CAP). Recommendations differ from a pathogen directed approach to an empirical strategy with broad spectrum antibiotics. Methods: In a prospective randomised open study performed between 1998 and 2000, a pathogen directed treatment (PDT) approach was compared with an empirical broad spectrum antibiotic treatment (EAT) strategy according to the ATS guidelines of 1993 in 262 hospitalised patients with CAP. Clinical efficacy was primarily determined by the length of hospital stay (LOS). Secondary outcome parameters for clinical efficacy were assessment of therapeutic failure on antibiotics, 30 day mortality, duration of antibiotic treatment, resolution of fever, side effects, and quality of life. Results: Three hundred and three patients were enrolled in the study; 41 were excluded, leaving 262 with results available for analysis. No significant differences were found between the two treatment groups in LOS, 30 day mortality, clinical failure, or resolution of fever. Side effects, although they did not have a significant influence on the outcome parameters, occurred more frequently in patients in the EAT group than in those in the PDT group (60% v 17%, 95% CI −0.5 to −0.3; p<0.001). Conclusions: An EAT strategy with broad spectrum antibiotics for the management of hospitalised patients with CAP has comparable clinical efficacy to a PDT approach.

Skin tests and histamine release with P1-depleted Dermatophagoides pteronyssinus body extracts and purified P1

Monoclonal antibodies were raised against P1 and Dp X, two major allergens in Dermatophagoides pteronyssinus extracts. The concentrations of IgE antibodies to P1 and Dp X in sera of mite-sensitive patients were determined in RAST with immunosorbent-bound monoclonal antibodies used for insolubilization of the allergens. The major allergen-specific IgE titers were compared with the total IgE response against D. pteronyssinus. The results of these serologic assays confirmed studies in the literature that P1 and Dp X are major allergens. The contribution of IgE anti-P1 to the total antimite response frequently exceeded 50% and, in general, appeared to be higher than the contribution of IgE anti-Dp X. Twenty percent of the mite-sensitive patients had no detectable IgE to either P1 or Dp X. The contribution of P1 to the biologic activity of D. pteronyssinus body extracts was derived from the effect of P1 depletion on the reactivity in the histamine-release test and skin test. This technique was preferred to the study of purified allergen because biologic activity of the nonabsorbed components is not affected. Immunization of rabbits with affinity-purified P1 yielded monospecific polyclonal antisera. Mite extracts depleted with either monoclonal or polyclonal anti-P1 were applied in the histamine-release test. The skin test was performed with extracts depleted with polyclonal anti-P1. In addition, the activity of affinity-purified P1 was investigated in these tests. The results indicated that P1 depletion of D. pteronyssinus body extracts had no detectable effect on the activity in most patients, namely, at least 70% of the activity was retained in the depleted extract. There was a considerable variation between patients in the sensitivity for purified P1, as compared to the sensitivity for whole D. pteronyssinus extracts. In the histamine-release test, the activity of purified P1 was up to 35% of the activity of the D. pteronyssinus body extract but did not exceed 10% in most patients. This was in agreement with the relative activity of purified P1, as found in the skin test. Therefore, the contribution of P1 to the biologic activity of D. pteronyssinus body extracts, as measured by end point titration, appeared to be less than expected on the basis of the serologic studies and articles in literature. The depletion experiments stress that there is still much uncertainty as to the biologic activity of house dust-mite extracts.

Antibiotics in addition to systemic corticosteroids for acute exacerbations of chronic obstructive pulmonary disease.

RATIONALE The role of antibiotics in acute exacerbations is controversial and their efficacy when added to systemic corticosteroids is unknown. OBJECTIVES We conducted a randomized, placebo-controlled trial to determine the effects of doxycycline in addition to corticosteroids on clinical outcome, microbiological outcome, lung function, and systemic inflammation in patients hospitalized with an acute exacerbation of chronic obstructive pulmonary disease. METHODS Of 223 patients, we enrolled 265 exacerbations defined on the basis of increased dyspnea and increased sputum volume with or without increased sputum purulence. Patients received 200 mg of oral doxycycline or matching placebo for 7 days in addition to systemic corticosteroids. Clinical and microbiological response, time to treatment failure, lung function, symptom scores, and serum C-reactive protein were assessed. MEASUREMENTS AND MAIN RESULTS On Day 30, clinical success was similar in intention-to-treat patients (odds ratio, 1.3; 95% confidence interval, 0.8 to 2.0) and per-protocol patients. Doxycycline showed superiority over placebo in terms of clinical success on Day 10 in intention-to-treat patients (odds ratio, 1.9; 95% confidence interval, 1.1 to 3.2), but not in per-protocol patients. Doxycycline was also superior in terms of clinical cure on Day 10, microbiological outcome, use of open label antibiotics, and symptoms. There was no interaction between the treatment effect and any of the subgroup variables (lung function, type of exacerbation, serum C-reactive protein, and bacterial presence). CONCLUSIONS Although equivalent to placebo in terms of clinical success on Day 30, doxycycline showed superiority in terms of clinical success and clinical cure on Day 10, microbiological success, the use of open label antibiotics, and symptoms. Clinical trial registered with www.clinicaltrials.gov (NCT00170222).

Value of intensive diagnostic microbiological investigation in low- and high-risk patients with community-acquired pneumonia.

In a prospective study to evaluate the diagnostic yield of different microbiological tests in hospitalised patients with community-acquired pneumonia, material for microbiological investigation was obtained from 262 patients. Clinical samples consisted of the following: sputum for Gram staining, culture, and detection of pneumococcal antigen; blood for culture and serological tests; urine for detection of Legionella pneumophila serogroup 1 antigen and pneumococcal antigen; and specimens obtained by fiberoptic bronchoscopy. A pathogen was identified in 158 (60%) patients, with Streptococcus pneumoniae (n=97) being the most common causative agent of community-acquired pneumonia. In 82% of the 44 patients with an adequate sputum specimen, a positive Gram stain was confirmed by positive sputum culture. S. pneumoniae infections were detected principally when adequate sputum specimens were examined by Gram stain and culture and when adequate and inadequate sputum specimens were tested for the presence of pneumococcal antigen (n=58; 60%). The urinary pneumococcal antigen test was the most valuable single test for detection of S. pneumoniae infections (n=52; 54%) when sputum pneumococcal antigen determination was not performed. Fiberoptic bronchoscopy was of additive diagnostic value in 49% of the patients who did not expectorate sputum and in 52% of those in whom treatment failed. Investigation of sputum by a combination of Gram stain, culture, and detection of pneumococcal antigen was the most useful means of establishing an aetiological diagnosis of community-acquired pneumonia, followed by testing of urine for pneumococcal antigen. Fiberoptic bronchoscopy may be of additional value when treatment failure occurs.

False-positive skin prick test responses to commercially available dog dander extracts caused by contamination with house dust mite (Dermatophagoides pteronyssinus)allergens ☆ ☆☆ ★ ★★

BACKGROUND In an outpatient population, a high frequency of positive skin prick test responses to dog dander was found in the absence of detectable IgE to dog dander in the RAST. The majority of these patients were sensitized to house dust mites (Dermatophagoides pteronyssinus) and had no obvious dog-related allergic symptoms. These findings prompted us to investigate whether dog dander skin test preparations are contaminated with house dust mite allergens in amounts sufficient to cause false-positive skin prick test responses in patients sensitized to house dust mites. METHODS Antigen detection assays with monoclonal and polyclonal antibodies were used to determine concentrations of the major allergen Can f 1 from dog dander and the major allergens Der p 1 and Der p 2 from house dust mites in five commercially available dog dander skin prick test preparations (A to E). RESULTS Can f 1 concentrations varied for the different extracts (A: 170 micrograms/ml, B: 11.1 micrograms/ml, C: 13.3 micrograms/ml, D: 3.8 micrograms/ml, and E: 59.4 micrograms/ml). Der p 1 was detectable in all extracts (A: 33.4 ng/ml, B:5.1 ng/ml, C:29.6 ng/ml, D: 0.4 ng/ml, and E: 1.9 ng/ml), and Der p 2 was detectable in some of the commercially available dog dander skin prick test preparations tested (A: 31.3 ng/ml, B: 3.0 ng/ml, and C: 7.5 ng/ml). The median house dust mite threshold in the skin prick test was found to be 5.8 ng/ml, of Der p 1 (range, 3.5 to 20.8 ng/ml) in nine patients tested. CONCLUSION Contamination of commercially available dog dander skin prick test preparations with the major allergens (Der p 1 and Der p 2) of the house dust mite (D. pteronyssinus) was demonstrated. These contaminations cause false-positive responses to skin prick tests with dog dander in patients sensitized to house dust mite.