Western blotting in evaluating Lyme seropositivity and the utility of a gel densitometric approach.

The antibody response to Borrelia burgdorferi is widely used in the diagnosis of Lyme neuroborreliosis and other manifestations of Lyme disease. However, a problem with immunoassays has been a significant number of false positives. The Western blotting technique is a useful adjunct in the serodiagnosis of other infections, but its use in Lyme borreliosis has been limited because of a lack of definition of what constitutes a positive assay. Using a gel densitometric analysis, we devised quantitative criteria for positivity and tested our criteria by matching blot results with clinical characteristics in a retrospectively studied group of 20 patients with Lyme disease, 23 healthy controls, and 18 patients with other neurologic and rheumatologic diseases. We then evaluated these criteria prospectively in serum from 35 ELISA-positive patients, and found that the serum from the majority of patients with positive serologies by ELISA were negative by Western blot. The Western blot-negative seropositive patients usually had other inflammatory or infectious diseases. We conclude that quantitative Western blotting is a helpful test in the serodiagnosis of Lyme neuroborreliosis and other manifestations of Lyme disease.