A 30-year-old female who recently returned from a hiking trip in the northeastern United States presents to her physician with a two-week history of a slowly expanding, erythematous rash with central clearing on her thigh. She also reports intermittent fatigue, arthralgias, and mild headache. Serological testing reveals a positive IgM and IgG response to Borrelia burgdorferi. Which of the following mechanisms is MOST significant in the pathogenesis of the clinical manifestations observed in this patient?