PROTECTIVE ANTIBODIES IN MURINE LYME-DISEASE ARISE INDEPENDENTLY OF CD40 LIGAND

Borrelia burgdorferi-infected mice develop acute arthritis that underg oes Ab-mediated resolution. To further investigate the role of B. burg dorferi-specific Abs in Lyme borreliosis, CD40 ligand-deficient (CD40L -deficient) mice were infected with B. burgdorferi. The development an d regression of arthritis were similar in CD40L-deficient and control mice. Although CD40L-deficient mice have defects in Ig class switching , infected CD40L-deficient mice developed B. burgdorferi-specific IgG2 b Abs. Moreover, the transfer of serum from B. burgdorferi-infected CD 40L-deficient animals prevented infection in severe combined immunodef icient mice. These data show that B. burgdorferi-infected CD40L-defici ent mice are capable of producing Abs that are protective, despite the inability of these mice to mediate T-dependent immune responses.