Non-Polarized Cell Surface Expression of Hla-A,B,C and Hla-Dr Antigens in Graves' Thyroid Follicle Cells

Abstract

The intrathyroidal distribution and cell surface location of HLA-A,B,C and HLA-DR antigens was studied in polarized thyroid follicle cells from Graves' (n=11) and normal (n=3) thyroid tissue, using light and electron microscopy. Cryosections and isolated, open follicle segments were incubated with monoclonal antibodies against HLA-A,B,C and HLA-DR antigens and with patient sera containing autoantibodies against the micro-somal antigen/thyroperoxidase. Immunoreactivity for HLA-A,B,C and HLA-DR on isolated thyroid follicle cells was frequently detected in Graves' disease, but absent in normal glands. There was a large variation in the immunolabelling between follicles as well as between different glands. Both HLA-A,B,C and HLA-DR immunoreactivity were detected on the apical and the basal surface of the follicle cells. Microsomal antigen/thyroperoxidase immunoreactivity was restricted to the apical cell surface. In contrast to normal tissue, HLA-DR positive cells with a dendritic or macrophage-like morphology were frequent in Graves' tissue. These cells adhered directly to the basal surface of isolated follicle segments. We conclude that HLA antigens are, unlike thyroid-specific plasma membrane constituents, expressed in a non-polarized manner at the surface of the follicular epithelium. These observations might have implications on the immune recognition of thyroidal autoantigens in Graves' disease.

Key Words:

• HLA antigens
• Graves' disease
• autoimmunity
• cell surface
• cell polarity
• immunocyto-chemistry