ABSTRACT
The immune response to individual major antigens of Legionella bozemanii was studied in 67 sera from 26 inpatients with febrile disease using immunoblotting techniques. All the patients had fever of unknown origin and showed strong serological reactions to L bozemanii that cross-reacted with Rickettsia typhi, as determined by a standard indirect microimmunofluorescence assay. Sera analysed by western blotting reacted with 12-14 molecular components of L bozemanii with apparent molecular weights ranging from 14,000 to 94,000 daltons. These reactions compared well with a reference system using antisera of rabbits immunised with the same strain of Legionella. The three major cross-reactive components of R typhi were polypeptide antigens of 94,000, 67,000 and 43,000 daltons. It is concluded that western blotting can help in the differential diagnosis of patients with fever of unknown origin whose sera cross-react to L bozemanii and R typhi.
Subject(s)
Antigens, Bacterial/immunology , Legionella/immunology , Legionellosis/immunology , Adult , Aged , Animals , Blotting, Western , Cross Reactions/immunology , Female , Fever of Unknown Origin/etiology , Humans , Immunoglobulin G/biosynthesis , Immunoglobulin M/biosynthesis , Legionellosis/complications , Legionellosis/microbiology , Male , Middle Aged , Molecular Weight , Rabbits , Rickettsia typhi/immunologyABSTRACT
The prevalence of seropositivity to Legionella spp. was studied in 184 children with bronchial asthma and in 80 control children, age- and sex-matched, without respiratory tract infections. The sera were examined by indirect immunofluorescence with antigens of six Legionella spp. The asthmatic children showed a significantly higher percentage of seroreactions to L. pneumophila than did 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 correlation could be found between the asthma severity score and the titer of serum antibodies to L. pneumophila. None of the 32 sera with titers of 256 or higher were reactive for Legionella-specific IgE antibodies. L. pneumophila antigen was detected in the urine of three children by an enzyme-linked immunosorbent assay (ELISA). The high prevalence of antibodies to L. pneumophila found in children with bronchial asthma, together with the detection of antigen in the urine of some of them, suggest that this group of children are highly susceptible to Legionnaires' Disease.
Subject(s)
Antibodies, Bacterial/analysis , Asthma/immunology , Legionella/immunology , Legionnaires' Disease/immunology , Adolescent , Child , Child, Preschool , Enzyme-Linked Immunosorbent Assay , Female , Fluorescent Antibody Technique , Humans , Male , RiskABSTRACT
The sera of 19 patients with a febrile disease of undetermined etiology were positive in the indirect immunofluorescence assay (IFA) to Legionella bozemanii serogroup 1 (Lb) and Rickettsia typhi (Rt). To both antigens, high titers of IgG-class and IgM-class antibodies were demonstrated. Several of the patients also had positive IFA and Weil-Felix reactions to Proteus vulgaris OX19 (PX 19). A sharp reduction of the serotiters to all three antigens was achieved by absorption of the sera with any one of the organisms. We demonstrated, by crossed immunoelectrophoresis with an Lb extract and a rabbit reference anti-Lb serum, that a heat-stable and trypsin-resistant antigen (antigen no. 1) reacted consistently with patients' sera that had been incorporated into an intermediate gel. Sera from five patients with high-titer IFA reactions to Rt, but no reaction to Lb, showed no interaction with antigen no. 1.
