Your immune system

Alan Edward Nourse (; August 11, 1928 – July 19, 1992) was an American science fiction writer and physician. He wrote both juvenile and adult science fiction, as well as nonfiction works about medicine and science. His SF works sometimes focused on medicine and/or psionics. His most notable pen name was Doctor X. He used this pseudonym when writing for a medical column in a science fiction magazine, allowing him to combine his expertise in medicine with his passion for science fiction.