A HISTOPATHOLOGIC AND IMMUNOLOGICAL STUDY OF THE COURSE OF SYPHILIS IN THE EXPERIMENTALLY INFECTED-RABBIT - DEMONSTRATION OF LONG-LASTING CELLULAR-IMMUNITY

  • 1 January 1980
    • journal article
    • research article
    • Vol. 101  (2) , 387-+
Abstract
The causative agent of syphilis, Treponema pallidum, was inoculated into the testes of rabbits. A rapid proliferation of organisms occurred in the interstitial tissues of the testes, reaching a maximum in about 10-11 days. Systemic spread of organisms primarily in the lymphoid organs was observed. A prompt immune response was manifested by hyperplasia of T cell domains in draining lymph nodes and spleen, blast transformation responses of lymphoid cells to sonicates of T. pallidum, the appearance of serum antibody, and the marked infiltration of the infected areas of the testes by T cells. Essential clearing of organisms (identified by immunofluorescence) from the infected site was observed 10-14 days after infection associated with evolution of the inflammatory response from primarily a T cell infiltrate to a larger mononuclear cell type. The immunofluorescent identification of presumptive T. pallidum antigen in macrophages was seen. Interstitial fibrosis or resolution 17-21 days after infection occurred. Examination of infected testes 1-24 mo. later revealed foci of tubular atrophy and fibrosis of varying size, alternating with regenerated tubules, separated by interstitial areas with only minimal fibrosis. During the long period of latency, there was no evidence of atrophy or hypoplasia of the lymphoid organs, and long-lasting T cell memory with regard to T. pallidum sonicates was demonstrable. Reinfection of previously inoculated rabbits indicated partial protection at 25 days after infection followed by essentially complete protection after 55 days. There was a prompt and long-lasting immune response to T. pallidum in experimentally infected rabbits. The main mechanism for destruction of infecting organisms appeared to be T-cell-initiated macrophage-mediated destruction, but a role for antibody dependent phagocytosis cannot be ruled out. The reason that some organisms may survive in various body organs remains unknown, but possible explanations were presented.