An immunotoxin of ricin A chain conjugated to thyroglobulin selectively suppresses the antithyroglobulin autoantibody response.

The autoantigen thyroglobulin has been conjugated with the A chain of the toxin ricin. In vitro this conjugated "immunotoxin" specifically suppressed the thyroglobulin autoantibody response of lymphocytes from patients with Hashimoto's thyroiditis. Neither total immunoglobulin synthesis nor the synthesis of autoantibody to thyroid microsomes by these lymphocytes was affected by the immunotoxin. The demonstration that an autoantigen coupled to a toxin can induce specific immunological unresponsiveness suggests that such immunotoxins could provide a novel and highly selective means for deleting autoantibody-secreting lymphocyte clones in patients with autoimmune disease.