"Autoimmunity" in rabbits. Sensitization to autologous ferritin by means of heterologous ferritin.

Rabbits that had received repeated subcutaneous injections of horse spleen ferritin in adjuvant developed antibodies that gave precipitin reactions with horse, rat, human and rabbit ferritins, including autologous ferritin from spleens of immunized animals. In the immunized animals, cutaneous Arthus reactions were readily induced with all of the cross-reacting ferritins, including autologous rabbit ferritin. The antibodies also sensitized healthy rabbits to rabbit ferritin as shown by the development of passive cutaneous Arthus reactions. These results underline the necessity of distinguishing between true autoimmunity, induced by an autologous immunogen, and `autoimmunity' induced by a foreign antigen related structurally to an autologous substance. To make this distinction with certainty, the primary immunogen must be known.