Autoimmune diseases induced by biological agents: a double-edged sword?

Biological agents are increasingly used for a rapidly-expanding number of rheumatic and systemic autoimmune diseases, with a growing number of reports of the paradoxical induction of autoimmune processes, overwhelmingly associated with anti-TNF agents. In this review, we analyze the clinical characteristics and outcomes of autoimmune diseases developing after biological therapies through a baseline Medline search as one of the objectives of the BIOGEAS project, created by the Spanish Society of Internal Medicine. The latest update of our registry (15 July 2009) included more than 800 cases of autoimmune diseases secondary to biological therapies, including a wide variety of both systemic (lupus, vasculitis, sarcoidosis and antiphospholipid syndrome) and organ-specific (interstitial lung disease, uveitis, optic neuritis, peripheral neuropathies, multiple sclerosis and autoimmune hepatitis) autoimmune processes. The majority of cases appeared between one month and one year after initiation of the biological agent and complete resolution was observed in nearly 75% of cases after cessation of therapy. The induced autoimmune diseases with the poorest outcomes were interstitial lung disease, inflammatory ocular disease and central nervous system demyelinating diseases.