Reovirus induction of MHC class II antigen in rat thyroid cells

We have previously demonstrated that cultured rat thyroid cells do not exhibit constitutive expression of major histocompatibility (MHC) class II antigens. Using reovirus types 1 and 3, we infected 1B-6 cells (a cloned derivative of the Fisher rat cell line FRTL-5), and found a dose-dependent induction of thyroid cell MHC class II antigen expression as determined by laser flow cytometry and FITC-labelled OX-6 anti-RT1.B. As the number of viral particles/cell used for the infections increased from 5 to 100, the number of antigen positive cells increased, in reovirus type 3 infections to 50%, and in reovirus type 1 infections to 15%. Kinetic studies indicated that MHC class II antigen expression continues to increase three days after infection. Viral infection and the resulting MHC class II antigen expression may allow presentation of thyroid antigen to the immune system and participate in the initiation of autoimmune thyroid disease.