In vitro cell response of Treponema pallidum-infected rabbits. I. Lymphocyte transformation.

Lymphocyte response to phytohaemagglutinin (PHA), Treponema pallidum, cultivable Reiter strain and cardiolipin reagent were examined using peripheral lymphocytes of T. pallidum-infected rabbits and control animals injected intratesticularly with saline extract of normal rabbit testes mixed with T. pallidum-free saline extract of infected testes. The response to PHA was significantly suppressed only in the infected animals, reaching the lowest level at 30 days after infection. A substantial increase of lymphocyte stimulation in the presence of cardiolipin reagent at 20 days after infection correlated well with the appearance of the maximum titre of Wassermann antibodies. Significant (P less than 0.02) increase in spontaneous response of cells incubated for 5 days made the response to T. pallidum and the Reiter strain difficult to interpret. An explanation for the spontaneous response is offered.