The role of protein component of T. pallidum in inducing skin reaction for delayed hypersensitivity.

The protein component of T. pallidum was shown to be an important agent in inducing the skin reaction for delayed type of hypersensitivity (SDH) in syphilis. Treponema preparations which contained T. pallidum deprived of this component by treating the organisms with merthiolate, formalin or heat, were found unable to produce a distinct positive skin reaction in syphilitic rabbits. Using preparations containing treponemes with preserved protein component, it was possible to induce the skin reaction for DH in rabbits as early as 4 weeks after inoculation of T. pallidum and during the subsequent 64 weeks of the infection (and of the observation period). The SDH was fairly well correlated with the results of the MMI test in the whole course of the syphilitic infection; a disagreement of results of these two tests occurred only between the 16th and 26th week of the infection.