Quantitation of isotype specific Haemophilus influenzae antibody in serum and saliva of normal subjects and chronic bronchitics.

An immunoglobulin isotype specific radioimmunoassay procedure has been developed to assess the antibody response to Haemophilus influenzae somatic antigens in serum and mucosal secretions. This assay was reproducible (between assay CV% 13.9; within assay CV% 4.5 IgG, 3.9 IgA, 3.0 IgM) and specific for H1/H2 antigens. Different patterns of antibody were observed in healthy children (aged 5-10 years), adults and patients with chronic bronchitis. In serum, 20% of chronic bronchitics had antibody levels greater than those observed in healthy adults. In saliva, the proportion of chronic bronchitic patients with high levels (greater than 12% binding) of IgG specific antibody was significantly greater (P less than 0.05) than in healthy adults or children. The proportion of children and chronic bronchitics which had antibody levels of up to 4% binding was significantly greater (P less than 0.05) than that observed in healthy adults. A similar pattern was observed for IgM specific antibody. The occurrence of IgA specific antibody in the saliva in children and chronic bronchitics was consistently greater than that observed in adults for all levels of antibody (P less than 0.05). Chronic bronchitics with high levels of antibody had greater infection and mortality rates.