SEROREACTIVITY TO BORRELIA-BURGDORFERI ANTIGENS IN THE ABSENCE OF LYME-DISEASE

Objective. To determine the background levels and specificity of antib ody to Borrelia burgdorferi by Western blot (immunoblot) in an area no nendemic for Lyme disease, and to correlate antibody specificity with clinical or serologic findings. Methods. In a prospective survey by co nsecutive sampling, serum was obtained from patients referred to a ter tiary care referral center in a rural area of Pennsylvania not endemic far Lyme disease. A total of 207 consecutive referrals to a rheumatol ogy clinic over a 3-month period from September, 1991 were divided int o 3 groups. Those referred because of a positive Lyme serology (Group 1) were compared with patients having positive antinuclear antibodies or rheumatoid factor (Group 2) and with controls having no rheumatic c omplaints (Group 3). Results. Antibody to at least one protein of B. b urgdorferi was seen in over 40% of patients. Reactivities to the heat shock proteins and the 41 kDa flagellar antigen accounted for the majo rity of positive bands. There were no differences observed between the 3 groups, and no significant correlation between Western blot and ELI SA findings in the absence of Lyme disease. Conclusion. We conclude th at significant levels of antibody to B. burgdorferi may be seen on Wes tern blotting in patients who have not been exposed to this organism b y clinical or epidemiologic criteria. The antibodies detected may be n atural antibodies, or may result from exposure to homologous antigenic epitopes on other organisms. The definition of a positive Western blo t in the diagnosis of Lyme disease should incorporate the background l evels of reactivity seen in nonexposed populations. Criteria for posit ivity should focus on the presence of antibody to the more specific pr oteins of B. burgdorferi.