DETECTION OF BORRELIACIDAL ANTIBODY BY USING ACRIDINE-ORANGE AND FLOW-CYTOMETRY

Borreliacidal antibody has been shown to be important for the serodiag nosis of Lyme disease and determination of immune status. Our results show that borreliacidal antibody can be rapidly and accurately detecte d by flow cytometry. Acridine orange was added to normal and immune se ra containing Borrelia burgdorferi organisms in the presence and absen ce of complement prior to data acquisition by flow cytometry. The flow cytometric parameters of side scatter and detection of acridine orang e fluorescence were used to determine events per minute (number of lab eled spirochetes), percent shift in fluorescence (number of dead spiro chetes), and mean channel fluorescence (intensity of fluorescence-labe led spirochetes) of acridine orange-labeled spirochetes. Borreliacidal antibody was detected as early as 4 h, with optimal detection 16 to 2 4 h after incubation of B. burgdorferi organisms with immune serum and complement. Our results also showed that complement was necessary for detection of borreliacidal antibody. Flow cytometry with acridine ora nge-labeled spirochetes provides a rapid means for detection of borrel iacidal antibody.