The effect of staphylococcal enterotoxin B on thyrocyte HLA molecule expression

Microbial superantigens have been implicated in the pathogenesis of human a utoimmune diseases. In autoimmune glands, thyrocytes inappropriately expres s HLA-DR molecules and these cells may function as antigen-presenting cells (APC) We studied the effect in vit ro of staphylococcal enterotoxin B (SEB ) on HLA molecule expression on thyrocytes obtained from autoimmune and non -autoimmune glands by immunofluorescence. HLA class I and class IT upregula tion could be detected by FAGS analysis on thyrocytes. Anti-IFN-gamma neutr alizing antibodies markedly affect both class I and class II upregulation o n thyrocytes. FRTL5 cells were not responsive to SEE. Similarly, a human th yroid cell strain maintained in culture in a conditioned medium was not ind uced to express HLA products by SEE, stimulation. The addition of autologou s intrathyroidal lymphocytes caused reestablishment of the SEE effect. (C) 1999 Academic Press.