NEW ANIMAL-MODELS FOR HUMAN AUTOIMMUNE THYROID-DISEASE - XENOGRAFTS OF HUMAN THYROID-TISSUE IN SEVERE COMBINED IMMUNODEFICIENT (SCID) AND NUDE-MICE

We have been employing two mouse models for the study of human thyroid xenografts from patients with autoimmune thyroid disease (AITD). The first mouse strain is that of the athymic ''nude'' mouse which accepts human thyroid xenografts, but the passenger lymphocytes are lyzed in this model over several weeks; in the second model, the severe combine d immunodeficient (SCID) mouse, both the xenograft and its lymphocytes survive. The AITD thyroid xenograft returns to normal function and mo rphology in the nude mouse over several weeks whereas the same AITD th yroid xenografts undergo aggravation of their lesions in the SCID mous e. Normalized (''cleansed'') thyroid tissue in the nude mouse, now ber eft of die passenger lymphocytes, can be removed and then re-xenograft ed into SCID mice. There it will remain normal unless autologous perip heral blood mononuclear cells are added, whereupon the AITD lesion wil l be reproduced. Autologous ''irrelevant'' muscle tissue having underg one the same process will not show such lesions. There is thus no evid ence for a primary thyroid cell disturbance in AITD, die abnormality a ppearing to be only in the immune system. Moreover peripheral blood mo nonuclear cells appear to contain sufficient memory cells to be able t o mount an immune assault on the autologous. normalized thyroid tissue (to which they had been previously sensitized) but not on irrelevant autologous (muscle) tissue.