While allergies are your body’s overreaction to specific antigens, they don’t constitute an autoimmune condition per se. As for psoriasis, no clear link to an autoimmune response has been established. In naturopathy, psoriasis is considered to be a toxicity problem.
When the organs responsible for elimination fail to remove all the toxins from your body, those that remain are sent to the skin for elimination. This excess is a major source of irritation for the skin. Check out the following links for information on allergies and psoriasis.