Bone-marrow chimeras reveal hemopoietic and nonhemopoietic control of resistance to experimental Lyme arthritis.

Both genetic resistance and susceptibility to development of experimental Lyme arthritis are mediated by the innate immune response. To determine whether this process is mainly controlled by hemopoietic or nonhemopoietic cells, we created bone marrow (BM) chimeric mice between arthritis-resistant DBA/2J (DBA) and arthritis-susceptible C3H/HeJ (C3H) mice and infected them with Borrelia burgdorferi. Both sets of BM chimeric mice, C3H donors into DBA recipients (C-->D) and DBA donors into C3H recipients (D-->C), as well as DBA sham chimeric mice (D-->D) were resistant to the development of experimental Lyme arthritis as measured by ankle swelling and arthritis severity scores. Only the C3H sham chimeric mice (C-->C) developed severe arthritis. These results indicate that independent and nonoverlapping mechanisms exist in hemopoietic and nonhemopoietic cellular compartments that can provide protection against arthritic pathology.