Counterimmunoelectrophoresis in the serodiagnosis of Legionnaires' disease.

Counterimmunoelectrophoresis (CIE) was found to be a rapid, specific method for detecting circulating antibodies to Legionella pneumophila, using a simple ultrasonically disrupted antigen. The diagnostic specificity of the technique was 93% and the diagnostic sensitivity was 86.3%. Both IgM and IgG classes of antibody can be detected. There is some cross-reactivity between serogroup 1 and serogroup 6 but none between serogroup 1 and serogroups 3, 4, and 5. It is suggested that CIE may provide a simple, reproducible screening test for Legionnaires' disease.