Toxic quinones produced by mammalian defense cells--causative agents for autoimmune reactions?

Multiple sclerosis is a disease both of the CNS compartment in which a localized immune response occurs, and of the peripheral immune compartment. The causative agent is unknown, though viruses are suspected to be among the candidates. Here a hypothesis is proposed, that apart from viruses, also activated granulocytes of the host might trigger a sensitization against self, insofar as they are suited to modify self-proteins. The modification results from the action of endogenous o-quinones which are generated by activated granulocytes. o-quinones are chemically reactive and couple to proteins producing new epitopes. Modified self-proteins then may sensitize the immune system or break the immune tolerance. Granulocytes thus not only effectively eliminate pathogens, but cause damage to tissues of the host, by proteinases as described in inflammation, or by endogenous o-quinones as proposed here for multiple sclerosis and its models.