Abstract

The immune system is composed of a variety of different cell types whose main task is defence against microorganisms, which can cause infection. Immune disorders are a group of disorders in which individual components of the immune system do not function properly. Immunodeficiencies are categorized as primary or secondary. Secondary immunodeficiencies are acquired and are more common than primary immunodeficiencies. Secondary immunodeficiencies are caused by external factors such as immunosuppressive therapy and some chronic diseases. Primary immunodeficiencies are a consequence of defects in the basic elements of the immune system, usually of genetic origin. Irrespective of the cause of the immunodeficiency, people with immune disorders are more prone to occasional or repeated serious infections.

Key words: immune system, immune response, infection, protection.