rambodoc.wordpress.com/…/21/sar-darky-jokes/ http://en.wikipedia.org/wiki/Immune_system Immune system From Wikipedia, the free encyclopedia Jump to: navigation , search A scanning electron microscope image of a single neutrophil (yellow), engulfing anthrax bacteria (orange). An immune system is a collection of mechanisms within an organism that protects against disease by identifying and killing pathogens and tumor cells.