Joints are often affected in Lyme disease and in some instances this may be due to immune autoreactivity. To characterise further the immune response in this disease investigations were carried out to determine the expression of three public idiotypes on serum immunoglobulins in patients with Lyme disease during the development of varying degrees of arthritis.
The expression of idiotypes (Ids) 16/6, BEG2, and PR4, first identified on monoclonal antibodies to DNA, was determined by an enzyme linked immunosorbent assay (ELISA) in serial blood samples from 12 patients with Lyme disease over a mean period of six years during the development of a variety of arthritic symptoms, and in serum samples from healthy control subjects and control subjects with systemic lupus erythematosus.
Expression of serum IgM or IgG public Ids 16/6 and BEG2 was significantly increased in patients with Lyme disease. IgA Id 16/6 expression, in contrast, was significantly increased only during episodes of arthritis and was also related to its severity. IgM and IgG Id 16/6 expression was related to their respective total immunoglobulin concentration and, in the case of IgM, to the level of IgM antibodies to Borrelia burgdorferi, whereas similar findings were not apparent with IgA antibodies. This may indicate that the IgA response is related to the pathogenesis of arthritis, especially as total IgA and IgA Id 16/6 levels were found to increase over the duration of disease. Sequential analysis of antibodies also showed restriction in the expression of Id 16/6 as it was never found on all immunoglobulin isotypes at the same time, and Id PR4 was never expressed. Ids 16/6 and BEG2 expression, however, may be associated as seven patients expressed these idiotypes simultaneously.
These data indicate the use of public idiotypes in the immune response against B burgdorferi, which may be restricted in terms of idiotype class and isotype expression, and a possible association between IgA antibodies bearing Id 16/6 with arthritis.