Lyme Disease: The Pitfalls of Laboratory Testing

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Currently available commercial tests for Lyme disease provide indirect evidence of exposure to the Lyme bacteria. When someone is infected with the Lyme bacteria, the immune system responds by making specific proteins, called antibodies, whose role is to seek out the Lyme bacteria, attach to them and initiate the process of destruction. In most patients, these antibodies are unable to destroy the Lyme bacteria (population, addition by J. Gruber), which by methods which are not completely understood, may remain alive in the human body for many years, in spite of high "titers" or concentrations of antibodies.

• Detectable levels of these antibodies may not be found until 3 to 8 weeks after exposure. Significant illness may be present before the test is positive.
• Most people who present with the characteristic EM (erythema migrans ) rash of Lyme disease test negative at that time.
• A number of patients clearly do not develop measurable antibodies. This is usually due to antibiotics given early in the infection for Lyme or non-Lyme infections.
• There is a significant strain variability in Lyme bacteria isolated in different geographic areas, and since commercial tests have been developed from certain isolates, they may be incapable of detecting antibodies to a different strain of Lyme bacteria.
• It is also possible that some people's immune systems do not recognize the Lyme bacteria as an invader and do not produce specific antibody .*
• When there is an excess of Lyme bacteria and their fragments, they may combine with all the circulating Lyme specific antibodies. Current commercial antibody tests for Lyme can only detect free circulating antibodies, and are incapable of detecting those bound up in immune complexes. Investigational tests have been developed to free these sequestered antibodies and render them measurable by the standard tests (Schutzer et al 1994).
• There is wide variability between tests of commercial laboratories, and it is not unusual to have a serum sample test positive in one lab and negative in another.
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• Some people who appear to be in good health and have no Lyme related symptoms may test positive.
  • This may indicate past exposure to the Lyme bacteria, with spontaneous recovery, or
  • it may represent a dormant infection which may activate at some future date and cause clinical disease.
  This has been well documented in the European literature.

The Western Blot is now commercially available for Lyme disease. Here various sized Lyme antibodies are allowed to migrate on a strip of filter paper. They separate into distinct bands, and serve as a 'fingerprint' for Lyme disease. This technique is wrongly thought to be a 'confirmatory test' for Lyme disease, which it is in AIDS. It may be useful to sort out false positive tests and in cases where the antibody titer is 'borderline'. Since its results depend on the presence of Lyme specific antibodies, the same factors which can cause a negative test may cause a negative 'Western Blot'.