Rhonda L Witte, BSc
The immune system is an elegant example of nature's work. When functioning properly, it protects us against what is "foreign" and does not attack the "self". Throughout an individual's life, changes occur within the immune system which make defense mechanisms less effective. Immunogerontology--the study of the aging immune system--is an up and coming field of research that will help build our knowledge, not only about the aging immune system, but also about the immune system in general.
The Immune System
Our immune system can be broken down into two interacting components: innate (natural) immunity and acquired (specific) immunity.1 Innate and acquired immunity differ regarding the effector cells and molecules that carry out their specific and essential functions. Natural immunity is composed of defense systems that are present before exposure to foreign macromolecules and infectious microbes. Physical barriers (i.e. the skin) phagocytic cells and eosinophils, a specific class of lymphocytes called natural killer cells, and a range of blood-borne molecules (i.e. soluble proteins of the complement cascade) make up the natural immune system.2 Acquired immunity requires stimulation by exposure to foreign molecules and includes sub-types of lymphocytes (e.g. B- and T-cells), cutaneous and mucosal immune responses and antibodies which circulate to find their target.