Rabbits exposed to female Ixodes dammini (both uninfected and infected with Borrelia burgdorferi) or injected with B. burgdorferi showed an acute inflammatory response in the skin. Granulocytes and monocyte-histiocytes were the predominant infiltrating cells. Spirochetes were detected in the tick feeding cavities in the deep dermis. The inflammatory process was accompanied by polyclonal antibody responses to tick salivary gland components. Western blots showed that immune rabbit serum reacted with proteins of molecular masses of 8, 24, and 36-41 kilodaltons in both unengorged and engorged tick salivary glands. Additional reacting bands in the immunoblot of the engorged salivary gland indicated that new antigenic components of the salivary gland are synthesized during engorgement. Rabbits did not produce antibodies to tick midgut components. Murine monoclonal antibody 11G1 detected outer surface protein A of B. burgdorferi in immunoblots of midguts from unengorged ticks, faintly in engorged salivary gland, and seldomly in unengorged salivary gland, findings suggesting that the spirochete is transmitted to the host via tick saliva during the later stages of feeding.