Lack of in vitro effect of antithyroid drugs upon peroxidase antigen expression in autoimmune thyroid disease
Aguayo, J.; Wohllk, N.; Baeza, A.; Pineda, G.
Revista Medica de Chile 121(10): 1105-1109
1993
ISSN/ISBN: 0034-9887 PMID: 7514805 Document Number: 412344
The aim of this study is to determine whether antithyroid drugs (ATD) act via inhibiting thyroid hormone synthesis or by interfering with the immune process which leads to autoimmune disease. Previously we had demonstrated that ATD do not affect HLA-DR and TPO antigen expressions induced by appropriate stimulus in normal thyrocytes, so we decided to study what happens when the same experiments are performed using autoimmune thyrocytes. Cultured thyroid tissue from patients operated on for Graves' Disease or Hashimoto's Thyroiditis were stimulated with TSH or TBII alone or associated with ATD; TPO antigen expression was evaluated by the Cytotoxicity Assay using human monoclonal antiTPO. When autoimmune thyrocytes were cultured and no stimulus was used or with the addition of MMI or PTU alone, very low values of TPO expression were noted (8.6 +/- 6.7, 5.0 +/- 7.1 and 4.2% +/- 2.3% respectively); if they were stimulated with TSH or TBII, a sharp rise of TPO antigen expression was detected (54.4 +/- 23.3 and 62.6 +/- 16.5%), these figures being significantly different from unstimulated cells (p < 0.001). If both stimulus were used associated with ATD, the high TPO antigen expression was unaffected. It is concluded that, at least in vitro, ATD have no effect upon induced-antigen expression in autoimmune thyrocytes. Since they do not alter antigen presentation, a primary step in the immune process, it is difficult to accept that their mechanism of action is through interference with the immune response.