Effect of removing human Graves' thyroid xenografts after eight weeks in nude mice and rexenografting them into SCID mice.

Abstract

Human thyroid xenografts from four patients with Graves' disease (GD) and two normal persons were initially xenografted into nude mice. Eight weeks after xenografting, the thyroid tissue appeared normal; indeed, thyroid infiltrating lymphocytes in the GD xenograft could no longer be identified when analyzed histologically. Thus, human immunoglobulin G (IgG), thyroperoxidase (TPO)-antibodies (Abs), thyroglobulin (Tg)-Abs, thyroid-stimulating antibodies (TSAb), and thyrocyte histocompatibility leucocyte antigen (HLA)-DR expression were undetectable. These same tissues were retrieved from the nude mouse and rexenografted into severe combined immunodeficient (SCID) mice (with no prior xenograft); autologous peripheral blood mononuclear cells (PBMC) or CD8-depleted PBMC (non-CD8 cells) were simultaneously injected into some of these SCID mice. Engraftment of a GD thyroid rexenograft (TH) alone did not cause IgG, TSAb, TPO-Ab, or Tg-Ab production, thyrocyte HLA-DR expression, or lymphocytic infiltration in thyroid grafts. Engraftment of GD PBMC or non-CD8 cells alone (i.e. without a thyroid xenograft) caused human IgG to rise, but only minimal titers of thyroid antibodies appeared. When TSAb, TPO-Ab, and Tg-Ab were quantified, GD TH plus PBMC-engrafted SCID mice showed significantly higher production of each antibody than that of GD PBMC alone, and this phenomenon was further enhanced by the removal of CD8+ cells. GD thyrocytes showed marked HLA-DR expression at human surgery; however, after 8 weeks' sojourn in nude mice, DR expression disappeared. After a further 8 weeks following rexenografting into SCID mice, TH plus PBMC resulted in a reappearance of DR expression only in GD but not in grafts from normal persons, and this was enhanced by the depletion of CD8 cells. These results were also in parallel with histological findings inasmuch as the normal tissue remained normal with no thyroid antibodies appearing with PBMC or CD8-depleted cells. In experiments from two GD patients, autologous skeletal muscle as well as thyroid tissue were xenografted into nude mice. Eight weeks after xenografting, these were rexenografted into SCID mice that contained prior autologous primary GD thyroid xenografts. Histological findings showed new lymphocytic infiltration in rexenografted thyroid tissues in the SCID mice but not in autologous skeletal muscle. This signifies that the immune assault in GD is specifically targeted to the thyroid tissue.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunologic Effects of Human Peripheral and Intrathyroidal Lymphocytes on Xenotransplanted Human Thyroid Tissue in Athymic Nude Mice

“…Furthermore, preliminary results of our group using a bioassay based on Chinese hamster ovary (CHO) cells has shown that these ITL initiate the production of thyrotropin receptor autoantibodies (67). Rexenografted GD thyroid tissue from nude mice to SCID mice, plus autologous PBL engraftment, caused thyroid antibody production and thyrocyte DR expression to rise (51). They reported a difference between AITD-PBL and AITD-ITL in reconstituted SCID mice depending on the antibody titers of patients (50).…”

Effect of Graves’ intrathyroidal lymphocytes

“…Thyrocytes in the engrafted human thyroid tissue can be stimulated and expression of class Il products and adhesion molecules can be induced by the invading human lymphocytes, which has also been demonstrated in SCID mice recently (Macht et al, 1991, Yoshikawa et al, 1994. These findings suggest that mainly ITL contain memory cells which must have returned to their thyroid target.…”

“…In SCID mice ITL derived from primary GD thyroid xenograft migrated to the autologous second thyroid xenograft. After rexenograftrnent of GD thyroid tissue from nude mice plus autologous PBL to SCID mice thyroid antibody production and thyrocyte DR expression can be induced (Yoshikawa et al, 1994).…”

Graves' disease / model of SCID mouse

“…In the latter circumstance, autologous PBMC were added in some animals but not others so as to compare the effect of adding PBMC to GD thyroid tissue that had been "cleansed" of its lymphocytes, through its sojourn in the nude mouse. lt may further be added that small pieces of sternomastoid muscle from the same human donor was also engrafted as an irrelevant tissue control (Yoshikawa et al, 1994a).…”

“…We have utilized this feature to retrieve the thyroid xenograft from GD patients after sojourn in the nude mouse (which then appears functionally and morphologically normal) and re-xenograft the same tissue into the SCID mouse. We have then been able to manipulate the immune environment by adding autologous peripheral mononuclear cells in various combinations so as to reproduce the immune disease in the graft de novo (Volpé etal., 1993;Yoshikawa et al, 1994a). This paper will briefly summarize our experience with the SCID mouse model with emphasis on studies of these secondary rexenografts.…”