T cell-mediated pathology in murine lyme borreliosis

Even in the absence of an appropriate model or direct evidence, T cells hav e been hypothesized to exacerbate the manifestations of Lyme disease. To de fine definitely the role of T cells in Lyme disease, the course of disease in immunocompetent and B cell-deficient mice was compared. By 8 wk postinoc ulation, immunocompetent mice resolved both carditis and arthritis, whereas foci of myocarditis and severe destructive arthritis characterized disease of B cell-deficient mice. Cell transfer experiments using infected B6-Rag1 knock out mice demonstrated that: 1) innate immunity mediated the initial sequelae of infection, 2) transferring both naive T cells and B cells induc ed resolution of carditis and arthritis, 3) infected mice reconstituted wit h T cells developed myocarditis and severe destructive arthritis, and 4) CD 4(+) T cells were responsible for the observed immune-mediated pathology. T hese data demonstrate directly the deleterious effect of T cells in Lyme di sease.