Heterogeneity of the immune status concerning anti-thyroglobulin antibody production among patients with Hashimoto's thyroiditis; an in vitro study

In vitro anti-thyroglobulin antibody (TgAb) production by unstimulated, thyroglobulin (Tg)-stimulated and pokeweed mitogen (PWM)-stimulated peripheral blood lymphocytes (PBL) from 44 patients with Hashimoto's thyroiditis and 10 normal individuals was investigated using a biotin-avidin enzyme-linked immunosorbent assay. Spontaneous TgAb production by non-T cells alone was observed in some patients. TgAb production induced by Tg was T cell-dependent and not accompanied by nonspecific IgG production. PBL from normal individuals produced no TgAb under any conditions. The patients were divided into four groups: 24 showed no TgAb production under any conditions, eight showed TgAb production only with PWM, seven produced TgAb spontaneously and more with both Tg and PWM, and five showed spontaneous TgAb production but no increase with Tg (four of these five patients showed an increase with PWM). Significant positive correlations between the serum TgAb titre and the amounts of TgAb produced by unstimulated, and Tg-stimulated and PWM-stimulated PBL were observed. It was suggested that spontaneous TgAb production was due to in vivo triggered antibody-producing B cells, while the TgAb produced only after in vitro Tg stimulation would be due to Tg-specific memory B cells helped by Tg-specific T cells. The increase in TgAb production due to PWM may be caused by activation of nonspecific helper T cells. These different PBL profiles probably reflect the heterogeneity of the immune status concerning TgAb production among patients with Hashimoto's thyroiditis.