Preservation of functioning human thyroid 'organoids' in the scid mouse. IV. In vivo selection of an intrathyroidal T cell receptor repertoire

To study the in vivo influence of thyroid cells on the T cell receptor repertoire in human autoimmune thyroid disease, we mixed lymphocyte-free thyrocytes (~1.2 x 10⁶) from patients with Graves' disease with autologous peripheral blood mononuclear cells (PBMC; ~1.5 x 10⁶) and transplanted this mixture sc into scid mice while suspended in a basement membrane gel (~0.4 ml). Controls included mice that received either thyrocytes only or PBMC only. The resulting artificial mixed cell thyroid organoids were explanted after 5 weeks, and their T cell receptor repertoire was examined. Of a total of 63 organoids constructed, 60 were recovered (95.2%). Total RNA was extracted and then analyzed by reverse transcription-PCR primarily for human T cell receptor (hTcR) Vβ gene expression using 21 hTcR Vβ amplimers. A restricted pattern of hTcR Vβ gene expression was found, with 6 Vβ genes (Vβ5, 6, 7, 8, 13.1, and 18) predominantly expressed [P < 0.05, by ANOVA on ranks and Student-Newman-Keul's (SNK) test]. PBMC and control organoids showed no preferential selection of particular hTcR V gene-expressing T cells. This reductionist, mixed cell, thyroid model reflected earlier observations in human and murine autoimmune thyroid diseases in which a bias in hTcR V gene family expression had been observed. The model permitted in vive T cell selection and/or enrichment of potentially disease relevant human T cells.