The effects of plasma from patients with Graves' disease on foetal mouse hearts in organ culture.

Plasma, obtained during plasma exchange therapy, from 3 euthyroid patients with Graves' disease and severe progressive exophthalmos induced an increase in heart rate and then early death when applied to foetal mouse hearts maintained in isolated organ culture. All plasma samples which induced an increase in foetal heart rate had high titres of thyroid stimulating immunoglobulins. Plasma samples obtained after exchange had a much diminished effect. These studies may indicate a previously unrecognized non-thyroidal action of the abnormal immunoglobulins associated with Graves' disease and suggest that chronic thyroid heart disease may be due, at least in part, to the effect of these immunoglobulins especially when not associated with elevated thyroid hormones concentrations.