Which medication is most likely to cause the production of autoantibodies?

Methyldopa is known for its ability to induce the production of autoantibodies, particularly in the context of drug-induced autoimmune hemolytic anemia. It is an antihypertensive medication that, when administered, can stimulate the immune system to produce antibodies that mistakenly target the body's own red blood cells, leading to hemolysis.

The mechanism by which methyldopa induces autoantibody formation is thought to involve the modification of red blood cell antigens, which makes the immune system recognize them as foreign. This often leads to the production of antibodies against these altered antigens, contributing to hemolytic disease.

In contrast, other medications listed, such as penicillin and cephalothin, are not primarily associated with autoantibody production. While they can cause allergic reactions or other immune responses, they do not typically lead to the formation of autoantibodies. Tetracycline, primarily used as an antibiotic, is also not recognized for causing such effects. Therefore, methyldopa stands out for its well-documented role in promoting the production of autoantibodies among the options given.