In vitro cell response of Treponema pallidum-infected rabbits. III. Impairment in production of lymphocyte mitogenic factor.

Production of mitogenic factor was examined in rabbits infected intratesticularly with T. pallidum and in control animals injected with saline or saline extract of normal rabbits' testes. Lymph nodes and spleen from animals killed 2, 6 and 12 weeks after injection were used as the source of lymphocytes, cultured in serum-free medium in the presence of Reiter antigen. The active supernatants of lymph node cells (LNAS) and spleen cells (SPAS) were examined for the presence of mitogenic factor using normal rabbit peripheral lymphocytes. The LNAS of control animals showed a mitogenic index (MI) between 4 and 6 and the infected animals less than 2. The SPAS of infected and control rabbits showed an MI of less than 2. The lower mitogenicity in LNAS of infected and that of SPAS of infected and control animals seems to be due to the presence of inhibitors of DNA synthesis.