Studies on the Serodiagnosis of Syphilis Application of Haemagglutination Test by the Treponema pallidum Specific IgM Antibodies

Treponema pallidum (Tp) organisms harvested from infected testes were purified by differential centrifugation. They were used as purified Tp antigens in several serological tests for syphilis, and showed stronger IgM reactivity than conventional crude Tp antigens. The new system using the purified Tp antigen improved the sensitivity to the sera from primary syphilitic patients from 45.5% to 97.7% in the TPHA test, and from 55.0% to 97.5% in the SPHA test. A unique method was devised to determine treponemal-IgM and the purified T. pallidum was also employed in the test. The method was named as the T. pallidum specific IgM heamagglutination test (TP-IgM-HA test), which employed erythrocytes sensitized with antisera to human IgM to separate IgM from IgG in serum. Specific anti-treponemal IgM captured in this way is detected by adding a second reagent comprising erythrocytes sensitized with the purified T. pallidum antigen. The sensitivity of the TP-IgM-HA test was 97.6% and the specificity was 99.7%. The test was not affected by rheumatoid factors and could detect treponemal IgM in sera from patients with reinfection. The TP-IgM-HA test will be a most effective fool not only for the early diagnosis but also in obtaining information on the neccessity and effect of the treatment of syphilis.