Abstract
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.