Factors that inhibit adherence of Treponema pallidum (Nichols strain) to a human fibroblastic cell line: development in serum of patients with syphilis.

Serum samples from 25 patients at five different stages of syphilis were investigated for their ability to inhibit the adherence of pathogenic Nichols treponemes to cultured human fibroblasts. Serum taken from patients at the end of the primary stage showed an appreciable inhibition of treponemal adherence, and maximum inhibition of adherence was produced by serum from patients with secondary syphilis. Some freshly harvested treponemal suspensions were resistant to the adherence inhibition factors in serum from patients with syphilis; after incubation in vitro for 24 hours this resistance was lost. In vitro incubation almost doubled the number of adherent treponemes/fibroblast. These phenomena are discussed in terms of loss and reconstruction of the treponemal outer envelope. This leads to the suggestion that adherence occurs not only at the tips of the treponemes, but that surface components are also implicated, possibly as an initial contact mechanism. The composition of the outer envelope may in this way determine localisation versus dissemination of the treponemes.

Autolymphocytotoxins in syphilis.

Nineteen of 23 serum samples from patients with secondary syphilis, six of 24 from patients with primary syphilis, and four of seven from patients with early latent syphilis had complement-dependent autolymphocytotoxic reactivity at 15 degrees C. After treatment, the reactivity was decreased. It was not directed only against autologous lymphocytes but also against allogeneic lymphocytes. Sephadex G-200 gel filtration showed that the lymphocytotoxins were present in the IgM-containing exclusion peak. Furthermore, serum samples that had high antibody titres in the Reiter protein complement-fixation test or Wassermann-Kolmer reaction also had a high frequency of cold-reacting autolymphocytotoxins. This indicates that the autolymphocytotoxic reactivity is related to the humoral response in syphilis.