Analysis of the humoral immune response to Treponema pallidum in the different stages of untreated human syphilis.

It has been shown that using treponema-specific and lipoidal assays for the demonstration of antibodies to Treponema pallidum subsp. pallidum in pooled sera of syphilitic patients, each stage of the untreated infection can be characterized by a typical immune response as far as specific immunoglobulin M (IgM) and G (IgG) antibody reactivity is concerned. In primary syphilis, IgM antibodies predominate over those of the IgG class. Moreover, IgM antibody reactivity with decreased titres can be detected in the later stages of untreated treponemal infection. Furthermore, it has been shown by using the double antibody radioimmunoprecipitation assay with detergent-solubilized [35S] methionine-labelled Treponema pallidum as antigen followed by sodium dodecyl sulphate polyacrylamide gel electrophoresis and autoradiography, that IgM and IgG antibodies in all stages of infection are directed against eight major antigenic proteins of Treponema pallidum with a Mr of 15,500, 33,000, 34,500, 37,000, 41,000, 44,500, 47,000 and 71,000.