Basic immunology: a primer

This article is intended to bring practicing physicians up to date on the current state of knowledge regarding the basic components and processes of the immune system. It discusses the role of the immune system and the importance of self-tolerance and describes the main cellular and noncellular entities involved in the immune response. It also details immune processes such as the lymphocyte selection process leading to self tolerance; antigen processing and presentation; cell signaling, activation, and co-stimulation; and the actions of cytokines and other signaling molecules.