EXPRESSION OF VARIOUS MHC CLASS-II MOLECULES AND OF INTRACELLULAR ADHESION MOLECULE-1 (ICAM-1) ON FOCAL CLUSTERS OF DENDRITIC CELLS IN IODINE DEFICIENCY GOITERS

Thyroid sections from 18 consecutive euthyroid patients undergoing sur gery for iodine deficiency goitre were investigated by means of immuno histochemistry and immunofluorescence, evaluating the expression of MH C class II antigens (HLA-DR, -DP, -DQ, and RFD1) and intercellular adh esion molecule-1 on the formerly described clusters of dendritic cells , as well as on thyrocytes. Eleven of 18 iodine deficiency goitres con tained clusters of dendritic cells. These clusters appeared to express only HLA-DR in two cases; in nine of 12 cases they showed a different ial expression of class II molecules in the following frequency: HLA-D R>DQ and/or -DP>RFD1. These dendritic cells also were ICAM-1+. In four of 18 iodine deficiency goitres, thyroid epithelial cells showed MHC class II expression in several combinations, but were ICAM-1-. In norm al thyroids and in nodular goitres from inhabitants of the endemic are a not having an actual iodine deficiency, only sparse clusters of dend ritic cells were found; these cells were only HLA-DR+. Follicle lining cells were negative for the MHC class II molecules. In normal thyroid s from an area with sufficient iodine supply, no clusters of dendritic cells were seen. The few dendritic cells observed were lying isolated in the interstitium and only positive for HLA-DR and ICAM-1; epitheli al cells were negative for the studied markers. These data show cluste rs of dendritic cells in thyroids of inhabitants of an endemic area. W hen goitre is accompanied by iodine deficiency at the moment of operat ion, there appears to be activation of these dendritic cells and of th yroid epithelial cells.