The protective function of cell-mediated immunity in syphilis.

: Experimental evidence has been obtained to show that the cell-mediated response in syphilis is protective. The use of chemical immunosuppressors (cyclophosphamide, 5-fluorouracil) resulted in the abolition of the cell-mediated response measured by the macrophage migration inhibition test (MMI test), and was accompanied by an enhancement in the severity of the lesions during the course of experimental syphilis in the rabbit. Successful adoptive transfer of resistance to syphilitic infection from immune donor rabbits to normal recipient rabbits employing lymph node lymphocytes was accomplished.