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Adaptive immunity to nontypeable Haemophilus influenzae
Paul T King1, Paul E Hutchinson, Paul D Johnson
1Department of Respiratory Medicine, Monash Medical Centre, Monash University, Melbourne. ptking@netspace.net.au
American Journal of Respiratory and Critical Care Medicine
|November 16, 2002
Summary
Chronic airway infections from nontypeable Haemophilus influenzae (NTHi) are linked to altered adaptive immunity. Healthy individuals show a Th1 response, while bronchiectasis patients exhibit a Th2 response, impacting disease progression.
Area of Science:
- Immunology
- Microbiology
- Pulmonology
Background:
- Nontypeable Haemophilus influenzae (NTHi) is a common colonizer of the upper respiratory tract.
- NTHi is a significant cause of infection in chronic obstructive pulmonary disease (COPD) and other chronic lung diseases.
- The adaptive immune response to NTHi is not well understood, particularly in the context of chronic infections.
Purpose of the Study:
- To test the hypothesis that recurrent airway infection with NTHi is associated with non-clearing adaptive immunity.
- To characterize the immune response to NTHi in healthy individuals and patients with idiopathic bronchiectasis.
- To investigate the role of adaptive immunity in the pathogenesis of chronic NTHi bronchial infections.
Main Methods:
- Study subjects included healthy control subjects and patients with idiopathic bronchiectasis and chronic H. influenzae infection.
- Antibody levels to NTHi were measured in all subjects.
- Antigen-specific T helper cell cytokine production and CD40 ligand expression were measured by flow cytometry.
- Immunoglobulin G subclass levels in peripheral blood were analyzed.
Main Results:
- All subjects, both healthy and those with bronchiectasis, had detectable antibodies to NTHi.
- Healthy control subjects exhibited a Th1 immune response to NTHi with significant CD40 ligand production.
- Subjects with bronchiectasis showed a predominant Th2 cytokine production, decreased CD40 ligand expression, and altered immunoglobulin G subclass profiles.
Conclusions:
- Chronic NTHi infection in bronchiectasis is associated with a distinct shift in adaptive immunity, characterized by a Th2-biased response.
- The observed changes in adaptive immunity, including cytokine profiles and CD40 ligand expression, may contribute to the pathogenesis of persistent bronchial infections in bronchiectasis.
- Understanding these immune alterations could inform therapeutic strategies for NTHi-related lung diseases.