The bacteria that cause Lyme disease appear to hide in the lymph nodes, triggering a significant immune response, according to researchers at the University of California, Davis.
However, the triggered immune response isn’t strong enough to destroy the infection. The National Institutes of Health –funded study conducted at the university, may explain why some people experience repeated infections of tick-borne Lyme disease.
“Our findings suggest that Borrelia burgdorferi, the bacteria that cause Lyme disease in people, dogs and wildlife, have developed a strategy for subverting the immune response of the animals they infect,” says Nicole Baumgarth a professor and authority on immune responses at the UC Davis Center for Comparative Medicine. “At first it seems counter intuitive that an infectious organism would choose to migrate to the lymph nodes where it would automatically trigger an immune response in the host animal, but B. burgdorferi have apparently struck an intricate balance that allows the bacteria to both provoke and elude the animal’s immune response.”
The UC Davis research team explored the mechanisms that cause enlarged lymph nodes and determined the nature of the resulting immune response.
Using mice, researchers found when animals were infected with B. burgdorferi, the live spirochetes accumulated in the animals’ lymph nodes. The lymph nodes responded with a strong, rapid accumulation of B cells, white blood cells that produce antibodies to fight infections. Also, the presence of B. burgdorferi caused the destruction of the architecture of the lymph node that usually helps it to function normally.
While B cells accumulated enough to make antibodies against B. burgdorferi, they did not form germinal centers, which are needed for the generation of highly functional and long-lived antibody responses.
The study appears online in the journal Public Library of Science Biology.