Studies on experimental iodine allergy: 2. Iodinated protein antigens and their generation from inorganic and organic iodine-containing chemicals.

We hypothesize that iodine allergy is an immune response to iodinated autologous proteins generated in vivo from iodine-containing organic and inorganic chemicals. In this report, effects of protein iodination on elicitogenic activity in guinea pig iodine allergy model and iodinated protein antigen generation in vitro from iodine-containing chemicals were investigated. Active cutaneous anaphylaxis (ACA) and delayed-type hypersensitivity (DTH) tests were performed in guinea pigs immunized with iodine. The amount of iodine (I2) reacted to proteins for giving them an eliciting activity of ACA was > or = 0.15 micromol for 1 mg of albumin. DTH reactions were provoked by intradermal injection of 10(6) PECs reacted with > or = 0.075 micromol of I2. I2 was generated from a potassium iodide (KI) solution or iodinated contrast media by UV light irradiation. X-ray irradiation of KI and iodinated contrast media in the presence of protein resulted in the generation of iodinated protein antigens. The generation of iodinated protein antigens was inhibited in the presence of reducing agents. Therefore, it is noteworthy that iodine allergy of the present hypothesis is dependent on reactive oxygens. By presenting these ex vivo and in vitro data, we discuss the possibilities for the generation of iodinated protein antigens in vivo.