Causes

Psoriasis may be one of the oldest recorded skin conditions। It was probably first described around 35 AD. Some evidence indicates an even earlier date. Yet, until recently, little was known about psoriasis.

While scientists still do not fully know what causes psoriasis, research has significantly advanced our understanding। One important breakthrough began with the discovery that kidney-transplant recipients who had psoriasis experienced clearing when taking cyclosporine. Since cyclosporine is a potent immunosuppressive medication, this indicates that the immune system is involved.

From http://www.skincarephysicians.com/psoriasisnet/whatis.html