The absence of a relationship between serum precipitins and pulmonary disease in a community

To study the role of serum precipitins in respiratory illness in a community, sera obtained from 3,047 residents of Tucson, Ariz., were tested for the presence of precipitating antibody to a battery of antigens. Positive reactions were obtained in 54 subjects (1.8 percent), a lower incidence than has been reported previously. The majority of these subjects were older than 54 years of age, an age distribution significantly older than the entire sample (P less than 0.01). Pulmonary function among the subjects with positive precipitin reactions was not significantly different from that of the asymptomatic nonsmokers of the entire sample. None of the subjects who were lifelong residents of Arizona had serum precipitins to any of the thermophilic actinomycetes antigens which were used in the testing. These antigens have been found in association with extrinsic allergic alveolitis, most frequently among patients living in the north central United States and were derived from strains of Micropolyspora faeni, Thermoactinomycetes candidus and vulgaris. Each subject with precipitins to one or more of the tested antigens was matched by age, sex, and socioeconomic class with two subjects from the sample who had negative precipitin reactions. The groups did not differ in their prevalence of respiratory symptoms or abnormalities of pulmonary function. We conclude that the presence of precipitating serum antibodies among subjects in a community is not indicative of the presence of immunologic pulmonary disease but merely reflects previous exposure to the tested antigen. In addition, individuals whose sera contain precipitating antibody appear to have no increased tendency to develop other types of pulmonary disease.