Inhibition of killer cell cytotoxicity induced by carbimazole in vitro.

The in vitro effect mediated by carbimazole (CBZ), a classical anti-thyroid agent on the antibody dependent cellular cytotoxicity (ADCC), low affinity E-rosetting cells (E-RFC) and high affinity E-RFC was investigated using lymphocytes from 11 normal subjects. CBZ at the doses of 250 and 500 mumol/l significantly reduced ADCC in all subjects studied. Low affinity E-RFC--mainly cells possessing receptors for the Fc portion of IgG and expressing cytotoxic properties in the ADCC system--were also significantly reduced following incubation with the same CBZ doses. These results suggest that CBZ, in addition to the known inhibitory effect on thyroid hormone synthesis, may be useful by depressing lymphocyte cytotoxicity in the treatment of autoimmune thyroid disease.