Induction of direct Coombs positivity with alpha-methyldopa in chimpanzees.

Two of four chimpanzees developed a moderately strong positive direct Coombs test after injection of stroma of their autologous erythrocytes that had been treated with alpha-methyldopa in the presence of diethyldithiocarbamate. Similar experiments with rabbits were unsuccessful. The results are concluded to be a demonstration that the first step in the development of autoantibody in alpha-methyldopa therapy is interaction of the oxidized drug with certain, as yet unidentified, peptides of the erythrocyte membrane.