The Hruska postulate of Crohn's disease

Crohn's disease is due to the loss of immunological tolerance within the gastrointestinal tract to the antigenic array of Mycobacterium avium subspecies paratuberculosis (MAP) and closely related polymorphic variants. The loss of immune tolerance results in an effector cytokine responsive upon re-exposure to MAP. For immune tolerance to MAP to be induced, infection must occur when acquired immunity is markedly underdeveloped.