3. Autoimmune hemolytic disease Some drugs or viruses stimulate Ab formation by changing the erythrocyte surface components to form new epitopes. The resulting Abs can cross react with epitopes on unmodified RBCs.3. Autoimmune hemolytic disease Some drugs or viruses stimulate Ab formation by changing the erythrocyte surface components to form new epitopes. The resulting Abs can cross react with epitopes on unmodified RBCs