Asthma and lower airway disease
The basophil surface marker CD203c identifies Aspergillus species sensitization in patients with cystic fibrosis

https://doi.org/10.1016/j.jaci.2015.07.045Get rights and content

Background

Colonization by Aspergillus fumigatus in patients with cystic fibrosis (CF) can cause A fumigatus sensitization and/or allergic bronchopulmonary aspergillosis (ABPA), which affects pulmonary function and clinical outcomes. Recent studies show that specific allergens upregulate the surface-expressed basophil marker CD203c in sensitized subjects, a response that can be readily measured by using flow cytometry.

Objective

We sought to identify A fumigatus sensitization in patients with CF by using the basophil activation test (BAT).

Methods

Patients with CF attending Beaumont Hospital were screened for study inclusion. BAT was used to identify A fumigatus sensitization. Serologic (total and A fumigatus–specific IgE), pulmonary function, and body mass index measurements were performed.

Results

The BAT discriminates A fumigatus–sensitized from nonsensitized patients with CF. Persistent isolation of A fumigatus in sputum is a significant risk factor for A fumigatus sensitization. Levels of the A fumigatus–stimulated basophil activation marker CD203c inversely correlated with pulmonary function and body mass index in A fumigatus–sensitized but not nonsensitized patients with CF. Total and A fumigatus–specific IgE, but not IgG, levels are increased in A fumigatus–sensitized patients with CF and ABPA when compared with those in A fumigatus–sensitized and nonsensitized patients with CF without ABPA. Itraconazole treatment did not affect A fumigatus sensitization.

Conclusion

Combining the BAT with routine serologic testing allows classification of patients with CF into 3 groups: nonsensitized, A fumigatus–sensitized, and ABPA. Accurate and prompt identification of A fumigatus–associated clinical status might allow early and targeted therapeutic intervention, potentially improving clinical outcomes.

Section snippets

Patient recruitment

We prospectively recruited 48 patients with CF to the study between October 2012 and October 2014. As control subjects, 11 healthy volunteers without CF were also recruited. Ethical approval was obtained from our institutional review board. CF was confirmed by sweat chloride levels (>60 mmol/L) and genotyping. Pulmonary function testing (see the Methods section in this article's Online Repository at www.jacionline.org) and serum sampling were performed on the day of the BAT. Total circulating

The BAT discriminates between nonsensitized and A fumigatus–sensitized patients with CF

Flow cytometry was used to measure basophil activation in response to A fumigatus. Basophils were gated as the Live/DeadCD3HLA-DRCD41aCD66bCD123+ population and evaluated for CD203c expression after A fumigatus extract stimulation (see Fig E1 in this article's Online Repository at www.jacionline.org). PBS and peanut extract were used as nonoffending and immunogenic controls, respectively. An arbitrary cutoff of 1.36 was determined by using the stimulation index of the control subjects

Discussion

The role of bacteria in the lungs of patients with CF has been extensively studied, and potential roles for fungi are beginning to emerge. Recently, much focus has been given to the wide spectrum of A fumigatus–associated morbidities in patients with CF, including A fumigatus sensitization and ABPA. Both of these clinical states are associated with poorer clinical outcomes.16, 31 For this reason, identifying patients with A fumigatus sensitization with or without ABPA is important to ensure

References (45)

  • C.L. Sokol et al.

    Emerging functions of basophils in protective and allergic immune responses

    Mucosal Immunol

    (2010)
  • A.F. Santos et al.

    Basophil activation test discriminates between allergy and tolerance in peanut-sensitized children

    J Allergy Clin Immunol

    (2014)
  • M. Cohen-Cymberknoh et al.

    Intravenous monthly pulse methylprednisolone treatment for ABPA in patients with cystic fibrosis

    J Cyst Fibros

    (2009)
  • V. Niederberger et al.

    Skin test results but not serology reflect immediate type respiratory sensitivity: a study performed with recombinant allergen molecules

    J Invest Dermatol

    (2001)
  • P. Valent et al.

    Assays for measuring in vitro basophil activation induced by recombinant allergens

    Methods

    (2004)
  • L. Delhaes et al.

    The airway microbiota in cystic fibrosis: a complex fungal and bacterial community—implications for therapeutic management

    PLoS One

    (2012)
  • K.L. Mortensen et al.

    Aspergillus species and other molds in respiratory samples from patients with cystic fibrosis: a laboratory-based study with focus on Aspergillus fumigatus azole resistance

    J Clin Microbiol

    (2011)
  • S.H. Chotirmall et al.

    Immunoevasive Aspergillus virulence factors

    Mycopathologia

    (2014)
  • S.H. Chotirmall et al.

    Aspergillus-associated airway disease, inflammation and the innate immune response

    Biomed Res Int

    (2013)
  • D.A. Stevens et al.

    Allergic bronchopulmonary aspergillosis in cystic fibrosis—state of the art: Cystic Fibrosis Foundation Consensus Conference

    Clin Infect Dis

    (2003)
  • A.P. Knutsen et al.

    Fungi and allergic lower respiratory tract diseases

    J Allergy Clin Immunol

    (2012)
  • J. Fillaux et al.

    Assessment of Aspergillus sensitization or persistent carriage as a factor in lung function impairment in cystic fibrosis patients

    Scand J Infect Dis

    (2012)
  • Cited by (0)

    Supported by Science Foundation Ireland via a United States–Ireland partnership (grant no. SFI/08/US/B1676) and by the US Cystic Fibrosis Foundation.

    Disclosure of potential conflict of interest: P. Murphy has received research support from the National Clinical Research Centre and Crumlin Hospital Dublin, has been supported by a National Children's Hospital joint grant on Metagenomics in Cystic Fibrosis, and is a board member for and has received travel support from Novartis. N. G. McElvaney has received research support from the Health Research Board and Science Foundation Ireland and has received consultancy fees from Chiesi and CSL Behring. The rest of the authors declare that they have no relevant conflicts of interest.

    These authors contributed equally to this work.

    View full text