Light chain distribution of anti-Borrelia burgdorferi IgG antibodies in Lyme arthritis

Abstract

Joint fluid (JF) and serum IgG from eight Lyme arthritis patients was investigated by isoelectric focusing, blotting to membranes of uncoated nitrocellulose (NC) as well as Borrelia (B.) burgdorferi antigen-coated NC (immunoblot) and immunoezymatic staining for visualization of the IgG isotype and characterization of the kappa/lambda light chain distribution. Oligoclonal bands of total IgG occurred in JF as well as in serum (3 cases) or in JF only (1 case); IgG lambda components were present in all four subjects and IgG kappa in three. IgG (Fc frag) reactive but kappa/lambda light chain negative oligoclonal bands were present in JF of one further patient. Additional investigations supported the interpretation that these components were free gamma chains. Oligoclonal anti-B. burgdorferi IgG antibodies occurred in JF as well as in serum (6 cases) or in JF only (1 case). There were complete identities, as defined by isoelectric points and light chain types, between JF and serum antibodies in an individual patient while identities between oligoclonal bands of total IgG and anti-B. burgdorferi IgG were infrequent. Antibodies of IgG kappa identity were present in all seven patients and six of them also had IgG lambda antibodies. The antibody response was, therefore, by definition oligo- and not monoclonal in 6 out of 7 patients. Furthermore, the anti-B. burgdorferi antibodies of IgG kappa identity only that were present in one case did not exhibit any completely characteristic monoclonal microheterogeneity.