LYMPHOCYTES IN PERIPHERAL BLOOD AND THYROID TISSUE IN CHILDREN WITH GRAVES' DISEASE

Abstract

OBJECTIVE: Our goal was to analyze interactions of lymphocytes in peripheral blood and thyroid tissue in children with Graves' disease (GD). METHODS: The prospective study concerned 15 children affected with GD and 15 healthy children. The levels of autoantibodies against thyrotropin receptor, thyroid peroxidase, and thyroglobulin were assayed. Monoclonal antibodies (Ortho Diagnostic Systems, Raritan, NJ) were used to define peripheral blood lymphocyte subsets and analyzed by using a flow cytometer. After thyroidectomy, thyroid specimens were stained with hematoxylin/eosin. T cells were detected by CD3+, CD4+, and CD8+ antibodies and the antigen-presenting dendritic cells with CD1a+ and CD35+ antibodies (DakoCytomation, Glostrup, Denmark). RESULTS: Before treatment, all children with GD had increased thyroid autoantibody levels, an increased percentage of CD4+ helper cells, and decreased levels of CD8+ suppressor/cytotoxic T cells, which resulted in an elevated CD4/CD8 ratio. The percentage of CD19+Cd5+ B cells was increased, although the total population of CD19+ B cells did not differ from that of the control group. The number of lymphocytes in the thyroid was decreased in 10 patients after long-term thiamazole treatment. In 5 patients with short-term therapy (<6 months after relapse of GD), the lymphocytes had formed lymphatic follicles: antigen-presenting dendritic cells CD1a+CD35+ in the germinal center and T-helper CD4+, T-suppressor CD8+, and B cells CD79+ on the edges. CONCLUSIONS: The primary defect of immunoregulation in GD consists of an increase of T-helper lymphocytes with a simultaneous decrease in the number of T-cytotoxic/suppressor cells. Thiamazole therapy probably leads to reduction of the lymphocyte amount in the thyroid.