Biotherapies refer to a new generation of medicines. On the model of natural biological molecules, they are similar or identical to proteins produced by the body (enzymes, proteins, antibodies). In autoimmune diseases, our body produces an excessive quantity of autoantibodies. We can then produce substances (antibodies, soluble receptors ...) capable of blocking the action of this autoantibody. Once administered, biotherapies specifically reach their target, a protein (BAFF or an antibody) to block or eliminate it...