INVASION AND CYTOPATHIC KILLING OF HUMAN-LYMPHOCYTES BY SPIROCHETES CAUSING LYME-DISEASE

Lyme disease is a persistent low-density spirochetosis caused by Borre lia burgdorferi sensu late. Although spirochetes causing Lyme disease are highly immunogenic in experimental models, the onset of specific a ntibody responses to infection is often delayed or undetectable in som e patients. The properties and mechanisms mediating such immune avoida nce remain obscure. To examine the nature and consequences of interact ions between Lyme disease spirochetes and immune effector cells, we co incubated B. burgdorferi with primary and cultured human leukocytes. W e found that B. burgdorferi actively attaches to, invades, and kills h uman B and T lymphocytes. Significant killing began within 1 hour of m ixing. Cytopathic effects varied with respect to host cell lineage and the species, viability, and degree of attenuation of the spirochetes. Both spirochetal virulence and lymphocytic susceptibility could be ph enotypically selected, thus indicating that both bacterial and host ce ll factors contribute to such interactions. These results suggest that invasion and lysis of lymphocytes may constitute previously unrecogni zed factors in Lyme disease and bacterial pathogenesis.