Borrelia burgdorferi-specific immune complexes in acute Lyme disease.

CONTEXT Diagnosis of infection with Borrelia burgdorferi, the cause of Lyme disease (LD), has been impeded by the lack of effective assays to detect active infection. OBJECTIVE To determine whether B. burgdorferi-specific immune complexes are detectable during active infection in LD. DESIGN, SETTING, AND PATIENTS Cross-sectional analysis of serum samples from 168 patients fulfilling Centers for Disease Control and Prevention surveillance criteria for LD and 145 healthy and other disease controls conducted over 8 years. Tests were performed blinded. MAIN OUTCOME MEASURE Detection of B. burgdorferi immune complexes by enzyme-linked immunosorbent assay and Western blot. RESULTS The B. burgdorferi immune complexes were found in 25 of 26 patients with early seronegative erythema migrans (EM) LD; 105 of 107 patients with seropositive EM LD; 6 of 10 samples that were seronegative [corrected] with culture-positive EM; 0 of 12 patients who were treated and recovered from LD; and 13 of 13 patients with neurologic LD without EM. Among 147 controls, B. burgdorferi immune complex was found in 0 of 50 healthy individuals; 0 of 40 patients with persistent fatigue; 0 of 7 individuals with frequent tick exposure; and 2 of 50 patients with other diseases. CONCLUSION These data suggest that B. burgdorferi immune complex formation is a common process in active LD. Analysis of the B. burgdorferi immune complexes by a simple technique has the potential to support or exclude a diagnosis of early as well as active LD infection.