Wikipedia:Today's featured article/March 1, 2007



The immune system is a set of mechanisms that protect an organism from infection by identifying and killing pathogens. This task is extremely difficult, since pathogens range from viruses to parasitic worms and these diverse threats must be detected with absolute specificity amongst normal cells and tissues. Pathogens are also constantly evolving new ways to avoid detection by the immune system and successfully infect their hosts. To meet this challenge, multiple mechanisms have evolved to recognize and neutralize pathogens. The immune systems of vertebrates such as humans consist of many types of proteins, cells, organs, and tissues, which interact in an elaborate and dynamic network. As part of this more complex immune response, the vertebrate system adapts over time to recognize particular pathogens more efficiently. The adaptation process creates immunological memories and allows even more effective protection during future encounters with these pathogens. This process of acquired immunity is the basis of vaccination. (more...)

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