Downregulation of class II molecules on epidermal Langerhans cells in Lyme borreliosis.

Background: Borrelia burgdorferi can be isolated from the skin of patients with acrodermatitis chronica atrophicans (ACA), a late-stage manifestation of Lyme borreliosis; despite a marked T-cell infiltrate in lesional skin and high antibody titres in patients' sera.

Objectives: To determine whether antigen-presenting Langerhans cells (LCs), which reportedly show signs of injury in erythema chronicum migrans (ECM), the early stage of disease, are altered in ACA.

Patients/methods: We studied the immunophenotype of cutaneous leucocytes on cryostat sections of lesional skin from both ECM and ACA patients.

Why is chronic Lyme borreliosis chronic?

Chronic Lyme borreliosis (CLB) can present not only in different organs but also in different patterns. Although many theories exist about the mechanisms leading to CLB, it is known that viable Borrelia burgdorferi can persist for decades and cause late skin manifestations of acrodermatitis chronica atrophicans (ACA). Thus, the immunopathogenetic findings in ACA can serve as a model for studying the chronic course of Lyme borreliosis.