According to the International Union of Immunological Societies, more than 150 primary immunodeficiency diseases (PIDs) have been characterized.
Soviet Union | European Union | Union Army | ATP International Series | rugby union | Union | International Monetary Fund | International Red Cross and Red Crescent Movement | ATP International Series Gold | International Space Station | Amnesty International | International Olympic Committee | BirdLife International | International Finance Corporation | International Organization for Standardization | International Telecommunication Union | International Criminal Court | trade union | One Day International | International Nonproprietary Name | International Labour Organization | International Civil Aviation Organization | International Boxing Federation | Union (American Civil War) | Toronto International Film Festival | International Atomic Energy Agency | Union Pacific Railroad | International Maritime Organization | International Development Association | England national rugby union team |