Effect of local and systemic macrophage activation in hamsters on infection with Treponema pertenue and Treponema pallidum Bosnia A.

The role of nonspecific macrophage activation in the destruction of treponemes needs to be defined. Studies have been hindered by an inability to confirm that macrophages have enhanced bactericidal activity at the site of treponemal infection. We show that subcutaneous and intravenous vaccination with BCG (Mycobacterium bovis) induces macrophage activation in hamsters, as determined by an enhanced ability to suppress the growth of Listeria monocytogenes in the livers, spleens, and inguinal lymph nodes. However, hamsters challenged in the inguinal region with Treponema pertenue during periods of enhanced microbial resistance (3 to 8 weeks after BCG vaccination) developed lesions faster and with more necrosis. Increased numbers of treponemes were recovered from the regional lymph nodes of BCG-vaccinated hamsters than from nonvaccinated controls, although the differences were not statistically significant. No pathological differences were detected in BCG-vaccinated and non-vaccinated hamsters challenged with Treponema pallidum Bosnia A. These studies demonstrate that BCG vaccination influences the pathogenesis of some treponemal diseases without inducing macrophage-mediated treponemicidal activity.