Cytokines (IL-4 and IFN-gamma) and antibodies (IgE and IgG2a) produced in mice infected with Borrelia burgdorferi sensu stricto via nymphs of Ixodes ricinus ticks or syringe inoculations

Mice were tolerant to tick bites during three infestations with nymphs of I xodes ricinus infected with Borrelia burgdorferi sensu stricto. To determin e whether tick bites influence the immune response;against B. burgdorferi, we examined the production of cytokines IL-4 and IFN-gamma by lymph node ce lls of BALB/c.mice and IL-4 deficient BALB/c mice after tick inoculation ve rsus syringe inoculation of B. burgdorferi. We also measured IgG2a anti;bor relial antibodies and total IgE in these mice. Results showed that BALB/c m ice developed a Th2 immune response against B. burgdorferi after tick inocu lation and a mixed Th1/Th2 response after syringe inoculation of B. burgdor feri. IL-4 deficient mice produced a Th1 immune response in both cases. IL- 4 produced following tick bites greatly decreased the production of anti-bo rrelial IgG2a antibodies by comparison with the production of anti-borrelia l IgG2a antibodies produced following syringe injection of B. burgdorferi.