DETECTION OF BORRELIACIDAL ANTIBODIES BY FLOW-CYTOMETRY - AN ACCURATE, HIGHLY SPECIFIC SERODIAGNOSTIC TEST FOR LYME-DISEASE

Background: Borreliacidal antibodies can be detected in serum samples from patients with early or late Lyme disease symptoms. When these ser um samples are incubated with Borrelia burgdorferi and complement, spi rochetes are rapidly killed. Detection of these antibodies can be used as a serodiagnostic test. Methods: Individual serum samples containin g IgM or IgG borreliacidal antibodies were used to develop a method fo r detection using flow cytometry. An additional 10 case-defined Lyme d isease serum samples and 10 normal serum samples were used to confirm appropriate flow cytometric parameters. To determine specificity, 157 normal serum samples and 104 potential cross-reactive serum samples we re tested for borreliacidal activity and antibodies to B burgdorferi u sing indirect fluorescent antibody or enzyme immunoassay. Results: Flo w cytometry can be used to detect borreliacidal activity within 16 to 24 hours after incubation of B burgdorferi organisms, Lyme disease ser um, and complement. Significant borreliacidal activity was detected in all Lyme disease serum samples. The percentages of positive normal se rum samples were comparable (6% to 10%) using all three assays. In add ition, the indirect fluorescent antibody and enzyme immunoassay identi fied 41 (39%) and 47 (45%) potential cross-reactive serum samples as p ositive, respectively. In contrast, significant borreliacidal activity was not detected in any potential cross-reactive serum samples. Concl usion: Detection of borreliacidal antibody, unlike indirect fluorescen t antibody and enzyme immunoassay, is an accurate, highly specific ser odiagnostic test for detection of Lyme disease.