17278 Hiroshi Arakawa/Huseyin Saribasak/Jean-Marie Buerstedde: Immunoglobulin-Genkonversion oder Hypermutation - das ist die Frage. Internet ca. 2005, 6p. Harald von Boehmer/Pawel Kisielow: How the immune system learns about self. Scientific American 265/4 (1991), 50-59. David Golde: The stem cell. Scientific American 265/6 (1991), 36-43. 5380 Avrion Mitchison: Will we survive? Scientific American September 1993, 102-108. Challenge to the immune system is presented by the rapid growth of the human population, the crowding together of many individuals in large cities, and the existence of high-speed means of travel. Such factors change our relationship to viruses, bacteria and parasites. Will the immune system retain the upper hand? Klaus Rajewski/Harald von Boehmer: Lymphocyte development. Current opinion in immunology 5 (1993), 175-176. 5367 Irving Weissman/Max Cooper: How the immune system develops. Scientific American September 1993, 32-39. The marvelous array of deftly interacting cells that defend the body against microbial and viral invaders arises from a few precursor cells that first appear about nine weeks after conception. From that point onward, the cells of the immune system go through a continuously repeated cycle of development. The stem cells on which the immune system depends both reproduce themselves and give rise to many specialized lineages - B cells, macrophages, killer T cells, helper T cells, inflammatory T cells. Environmental and genetic signals cue cells as they differentiate into the many lineages that recognize foreign antigens and fight off invaders.