Immunity

Immunity is the capability of multicellular organisms to resist harmful microorganisms. This involves both specific and non-specific components. The non-specific components act as barriers or eliminators of a wide range of pathogens irrespective of their antigenic make-up. Other components of the immune system adapt themselves to each new disease encountered and can generate pathogen-specific immunity.

Overview

An immune system may contain innate and adaptive components. The innate system in mammalians, for example, is composed of primitive bone marrow cells that are programmed to recognise foreign substances and react. The adaptive system is composed of more advanced lymphatic cells that are programmed to recognise self substances and non-self substances and are able to generate a global response to non-self substances.

The immune system is divided into a more primitive innate immune system, and acquired or adaptive immune system of vertebrates, each of which contains humoral and cellular components.

Innate Immunity

Innate immunity, also known as natural or genetic immunity, involves the body's natural resistances to disease, which can be non-specific and specific. This form of immunity is present at birth and provides the first line of defense against infection.

Adaptive Immunity

Adaptive immunity, on the other hand, involves the lymphocytes and develops as people are exposed to diseases or get immunized through vaccines. This form of immunity is also referred to as acquired immunity and is generally long-term.

Immune System Disorders

Some people may have immune system disorders in which their immune system is either overactive and attacks normal cells in the body, or it is underactive and unable to protect the body from infections and diseases.

See Also

• Innate immunity
• Adaptive immunity
• Immune system disorders