Studies of the effect of suppressor T lymphocytes on the induction of antithyroid microsomal antibody-secreting cells in autoimmune thyroid disease.

The suppressor function in CD8 (suppressor/cytotoxic) T lymphocytes from patients with autoimmune thyroid disease and normal subjects has been studied. CD8 and CD4 (helper/inducer) cells were separated by the panning method. Patient's non-T cells and autologous CD4 cells were cultured with or without autologous or allogeneic CD8 cells in the presence of either pokeweed mitogen or Staphylococcus aureus strain Cowan 1 plus human thyroid microsomal antigen. Antithyroid microsomal antibody (AMA) and total immunoglobulin G (IgG)-secreting non-T cells were measured by enzyme-linked immunosorbent spot assay. With pokeweed mitogen stimulation, the suppressor effect of CD8 cells from patients with serum AMA on the induction of AMA (of IgG type)-secreting cells was significantly less than that of CD8 cells from normal subjects. CD8 cells from patients with no serum AMA suppressed the induction of AMA-secreting cells as much as did normal CD8 cells. CD8 cells from both patients and normal subjects suppressed the induction of IgG-secreting cells equally well. On the other hand, with the combination of S. aureus strain Cowan 1 and human thyroid microsomal antigen (1 mg/L) stimulation, CD8 cells from both normal subjects and patients only slightly suppressed the induction of IgG-secreting cells. However, under these circumstances, once again, CD8 cells from both normal subjects and patients with no serum AMA suppressed the induction of AMA-secreting cells, whereas CD8 cells from patients with serum AMA suppressed the induction of the AMA-secreting cells significantly less. Higher TMc concentrations enhanced the suppressor effect of CD8 cells from patients with serum AMA on the induction of AMA-secreting cells. Furthermore, Concanavalin A, when added to the stimuli described above, further inhibited the induction of both AMA- and IgG-secreting cells by CD8 cells from patients with serum AMA. There thus appears to be a relative defect of antigen-specific suppressor T lymphocyte function in CD8 cells from patients with autoimmune thyroid disease, which may result in the presence of autoantibody-secreting cells in those patients.