Principles of Immunology

• Vertebrates, including humans, are continuously exposed to microorganisms, their products, and other foreign molecules from other sources, which raises a defensive response throughout the body, known as the immune response.
• The term immunity is derived from the Latin word immunitas, which was used for the first time for the family and relatives of Julius Caesar.
• Immunity refers to the cellular and molecular events that occur after an organism encounters microbes and other foreign macromolecules.
• Immunology deals with immunity to infectious agents, allergy and autoimmune diseases.
• The immune response differentiates self and non-self (antigens) and gives response to eliminate non-self.
• The immune system constitutes of cells and tissues that produce the immune response.
• The immune response can be divided into two main functional systems: Innate (Non-Specific) immunity and Acquired (specific) immunity.
• Thucydides, a Greek Historian, in Athens during the fifth century BC, first mentioned immunity to an infection that he called “plague”.
• The ancient Chinese custom of making children resistant to smallpox by having them inhale powders made from the skin lesions of patients recovering from the disease is an example of immunology.
• Explanations of immunologic phenomena are based on experimental observations and the conclusions drawn from them.
• The first clear example of the manipulation of the function of the immune system was Edward Jenner’s successful vaccination against smallpox in 1749.
• On 8 May 1980, during the Thirty-Third World Health Assembly, smallpox was declared to have been eradicated.
• All immune system cells originate from bone marrow.
• Nonspecific immune response mechanisms are inherited, they are the first line of defense against foreign (harmful) molecules, and include general (Nutrition, Age, Race), physical (mechanical) barriers, chemical barriers (Secretions), and biological barriers (Normal flora, cells).
• The mechanisms of innate immunity provide the initial defense against infections.
• Adaptive immune responses develop later and consist of activation of lymphocytes.
• Active immunity is conferred by a host response to a microbe or microbial antigen, whereas passive immunity is conferred by adoptive transfer of antibodies or T lymphocytes specific for the microbe.
• Both forms of immunity provide resistance to infection (immunity) and are specific for microbial antigens, but only active immune responses generate immunologic memory.