Immunology Course Outline - Session 1 The Cast of Characters - Review of Histology, Anatomy, and Terminology There are a variety of cellular and tissue components of the human immune system. Mammals have highly developed immune systems, compared with other creatures. For example, reptiles have a circulating cell known as a hemohistiocyte that functions both to carry oxygen and to fight infection-and it doesn't do a great job of either, somewhat like software programs that promise more than one function. Of the mammals, the primates have the most highly developed immune systems. However, complexity also carries with it the possibility of problems, both from loss of function (immunodeficiency) and from abnormal function (autoimmunity, neoplasia). The fancier the plumbing, the easier it is to stop up the drain. The Major Organs of the Immune System Cells of the Immune System Major Histocompatibility Complex Peripheral Blood Components Sets of Laboratory Findings to Interpret Return to the Immunology Course Outline