Lymphoproliferative responses to Borrelia burgdorferi in Lyme disease.
 OBJECTIVE: To compare lymphocyte proliferative responses to Borrelia burgdorferi in healthy controls and patients with Lyme disease.
 PATIENTS: Twelve patients fulfilling case-definition criteria for Lyme disease.
 Twelve healthy volunteers and two newborns served as controls.
 MEASUREMENTS: Antibodies to B.
 burgdorferi were measured by enzyme-linked immunosorbent assay (ELISA).
 Proliferation of peripheral blood lymphocytes cultured for 5 days with B.
 burgdorferi, recall antigens, or pokeweed mitogen was measured by radioactive thymidine uptake.
 RESULTS: Lymphocytes from 11 patients with Lyme disease, 8 healthy seronegative controls, and two newborns showed elevated responses when stimulated with B.
 burgdorferi.
 When a patient and a control were studied on the same day, the patient's lymphocyte response to B.
 burgdorferi exceeded the control's in only 5 of 12 cases.
 Lymphocytes from both patients and controls responded to B.
 burgdorferi isolates from three different sources.
 CONCLUSIONS: Heightened lymphocyte responses to B.
 burgdorferi are found in patients with Lyme disease but elevated responses also frequently occur in healthy controls.
 At present, the interpretation of a positive lymphocyte response to B.
 burgdorferi would be difficult in ambiguous clinical situations.
