In a recent peanut allergy study at Addenbrookes Hospital in Cambridge, traces of peanut flour were used to desensitise 18 highly peanut allergic children. At the end of the study conducted in a controlled hospital environment, they were able to consume 12 peanuts each without any allergic reaction. The study involved eating minute trace amounts of peanut flour mixed with food or drinks on a daily basis to slowly induce peanut tolerance. Then at regular 2 weekly intervals the peanut flour dose was doubled so that by the 10th hospital visit, they each ate 5-6 peanuts each without reacting on allergy testing. But to maintain thispeanut tolerance they will have to continue eating peanuts regularly on a daily basis, otherwise they may lose this tolerance and their peanut allergy recur.
WARNING: This was a highly controlled study in hospital and peanut allergic children should not be given peanut flour unsupervised!
http://news.bbc.co.uk/2/hi/health/7899383.stm