Intrathyroidal Activated (Ia⁺) T-Lymphocyte CD⁺ Subsets and B Cells in Graves' Hyperthyroidism Respond Rapidly to Propylthiouracil Therapy: Demonstration using Fine Needle Aspirates and Two-Colour Laser Flow Cytometry

Abstract

Using a rapid (whole blood lysis) single laser microfluorocytometric technique that permitted the simultaneous analysis of two monoclonal antibody surface markers tagged with different fluorescent dyes, the intrathyroidal (IT) and peripheral blood (PB) activated [Ia⁺=DR⁺] T-lymphocyte CD3⁺ subsets and [F(ab′)₂⁺] B cells were studied in hyperthyroid patients with Graves' disease (GD) before and after 1-4 months of propylthiouracil (PTU) therapy. IT lymphocytes were obtained by serial fine needle aspiration. In untreated patients a marked quantitative (≈< 10 fold) increase in activated (Ia⁺ CD3⁺) T-lymphocytes as well as CD4⁺ and CD8⁺ subsets, for IT compared to PB sites, was found. The percentages of Ia⁺ CD4⁺ and Ia⁺ CD8⁺ within Ia⁺ CD3⁺ were not significantly different between the two sources of T cells. F(ab′)₂⁺. B cells were significantly increased (≈2-3 fold) in IT compared to PB. In hyperthyroid GD patients, PTU therapy induced rapid and specific changes within the Ia⁺ CD3⁺ subsets, namely a reduction in the Ia⁺ CD4⁺ subset and an increase in the Ia⁺ CD8⁺ subset, resulting in a marked decrease in the Ia⁺ CD4⁺/Ia⁺ CD8⁺ ratio. These changes occurred in association with a reduction in serum T4 and T3 concentration. No significant changes could be detected within the total (predominantly non-activated) CD3⁺, CD4⁺ or CD8⁺ lymphocyte subsets within PB and only a small decrease in the CD4⁺/CD8⁺ ratio was demonstrated in IT, following PTU treatment.

The feasibility of measuring intrathyroidal Ia⁺ CD3⁺ T-lymphocytes subsets and B cells in GD patients has been established utilizing fine-needle aspirates and a rapid whole blood lysis and two-colour monoclonal antibody labelling, single laser, microfluoreocytometric technique. These studies also demonstrate that, since the numbers of intrathyroidal activated la⁺ T-Iymphocytes and B cells are greater than those in peripheral blood, the acute therapeutic effects of PTU on Ia⁺ CD3⁺ T subsets and B cells in Graves⁺ hyperthyroidism are more clearly demonstrated by studies from IT rather than PB samples.

Key Words:

• Ia⁺ (DR⁺) T-lymphocyte subsets
• B cells
• Graves⁺ hyperthyroidism
• propylthiouracil
• fine needle aspiration biopsy
• laser flow cytometry