Chlamydia pneumoniae Induces Interferon Gamma Responses in Peripheral Blood Mononuclear Cells in Children with Allergic Asthma.

Respiratory infections caused by Chlamydia pneumoniae have been associated with exacerbations of asthma. Cell-mediated immunity (CMI) is critical for maintaining immunity. We compared interferon (IFN)-γ responses in C. pneumoniae-infected peripheral blood mononuclear cells (PBMC) in paediatric patients ± asthma. Presence of C. pneumoniae was tested from asthma patients (N = 17) and non-asthmatic controls (N = 16) (PCR). PBMC were infected for 1 h ± C. pneumoniae AR-39 (MOI = 0.1) and cultured for 48 h. IFN-γ levels were measured in supernatants (ELISA). C. pneumoniae-IgG antibodies in serum were determined (MIF). All subjects tested negative for C. pneumoniae (PCR). C. pneumoniae-induced IFN-γ production in vitro was more prevalent in asthma compared with non-asthma; levels of IFN-γ were higher in asthma compared with non-asthma (P = 0.003). There was no association between recent respiratory infection and positive IFN-γ responses. These data show that C. pneumoniae modulates IFN-γ responses in patients with asthma, even in absence of active infection.