Serum antibodies to Legionella agents in bronchial asthma.

The prevalence of seropositivity to Legionella species was studied in 184 children with bronchial asthma and 80 control children, age and sex matched, without respiratory tract infections. The sera were examined by indirect immunofluorescence with antigens of six Legionella species. The asthmatic children showed a significantly high percentage of seroreactions to L pneumophila compared with the control children. In the asthmatic children, no association was found between age, sex, onset of asthmatic symptoms, living conditions, corticosteroid treatment, or exposure to aerosols and seropositivity to Legionella. No relation could be found between the asthma severity score and the titre of serum antibodies to L pneumophila. None of the 32 sera with titres of 1:256 or higher were reactive for Legionella specific IgE antibodies. A high prevalence of antibodies to L pneumophila was found in children suffering bronchial asthma. Further studies are necessary to clarify the clinical relevance.