Potassium cyanate, an in vitro inhibitor of lymphocyte blast transformation without in vivo activity.

Potassium cyanate (400 mug/ml) inhibited the blastogenesis of lymphocytes in response to PHA and the response of lymphocytes in mixed lymphocyte cultures. Cyanate administered to mice at a dose of 30 mg per kg per day did not delay allograft rejection.