Introduction to Immunology

What is Immunity?

Immunity means protection from disease and especially infectious disease. Cells and molecules involved in such protection constitute the immune system and the response to introduction of a foreign agent is known as the immune response. Immune response areproduced primarily by leucocytes, of which there are several different types. Not all immune responses protect from disease; some foreign agents, such as the allergens found in house dust mite, cat dander or pollen from certain trees, cause disease as a consequence of inducing an immune response. Likewise some individuals mount immune responses to their own tissues as if they were foreign agents. Thus, the immune response can cause the autoimmune diseases common to man such as multiple sclerosis, diabetes, rheumatoid arthritis or myasthenia gravis. Myasthenia gravis is a neuromuscular disorder characterized by variable weakness of voluntary muscles, which often improves with rest and worsens with activity. The condition is caused by an abnormal immune response. Most individuals do not suffer from autoimmune disease because they have developed tolerance towards their own (self) tissues.

Memory, specificity & the recognition of “non-self”
– these lie at the heart of immunology.

Immunologist experience of the subsequent protection (immunity) afforded by exposure to many infectious illness can lead them to this view.

An important characteristic of the immune system is that the cells are
able to distinguish “self” and “non-self”