[Development of anti-Treponema pallidum-IgM antibodies detection methods using purified antigen--comparison with...

Treponema pallidum subsp. pallidum Nichols (Tp) antigens were purified by centrifugation in the presence of Hypaque (sodium diatrizoate) or MgCl2. When the TPHA (Treponema pallidum hemagglutination) tests with crude and purified antigens were carried out in the sera of patients with untreated primary syphilis, the purification by MgCl2 resulted in enhanced sensitivity to Tp-specific IgM as the same as the purification by Hypaque. In addition, the SPHA (solid phase hemadsorption) test with the Hypaque-purified antigen to anti-Tp-IgM antibodies was carried out using the sera of patients with primary and secondary syphilis. Fifty-nine percent (27/46) of them showed positive for the crude antigen and 100% (46/46) for the purified antigen, indicating that sensitivity to anti Tp-IgM was clearly enhanced with the antigen purification. The captured Tp-IgM-RIA test with the purified antigen was also undertaken in 16 patients with primary syphilis, 31 patients with secondary syphilis and 73 patients with latent syphilis. All the patients in the former two groups were positive, while all of the patients in the latter group were negative. To elucidate the mechanism whereby the purification improves the sensitivity to anti-Tp-IgM antibodies, host-derived antibodies associated with crude and purified Tp cells were measured by a fluorescent antibody technique. As the results, a great amount of rabbit anti-Tp-IgM antibodies were found on the surface of the crude antigen, whereas only a trace amount was detected on the purified antigens.(ABSTRACT TRUNCATED AT 250 WORDS)