Stimulation of the growth of "normal" thyrocytes by lymphocytes infiltrating the tissue of diffuse toxic goiter

Abstract

The capacity of lymphocytes isolated from diffuse toxic goiter (DTG) tissue to stimulate the proliferation of normal thyrocytes isolated from paranodular tissue adjacent to nodular euthyroid goiter was studied. Normal and DTG thyrocytes were incubated for 24 h with fetal calf serum (FCS) in various concentrations, DTG orparanodular lymphocytes, or both FCS and lymphocytes. The proliferation rate of normal thyrocytes in the presence of FCS alone increased with increase of the serum concentration, while the proliferation rate of DTG thyrocytes did not depend on the concentration of FCS. DTG lymphocytes, but not paranodular ones, stimulated the proliferation of normal thyrocytes. The growth-stimulating effect of DTG lymphocytes was paralleled by loss of normal thyrocytes sensitivity to growth factors (FCS). These data indicate a probable role of intrathyroid lymphocytes in increase of thyrocyte count characteristic of DTG and confirm a previous hypothesis on decrease in expression of surface antigens (receptors) on DTG cells under the effect of intrathyroid lymphocytes.