However, in Tp0954-immunized rabbits, a much higher level of Th1 cytokine IFN-γ from splenocytes and proliferative response specific to rTp0954, as well as increased inflammatory infiltrations of lymphocytes and macrophages, indicate that an effective cellular immune response to T. pallidum was developed at the local infection site, which could lead to phagocytosis of spirochetes by resident macrophages activated by IFN-γ produced predominantly by effector CD4+ Th lymphocytes. The gene discussed is CD4; the disease is infection.