The localized desensitization which may take place after one has produced a reaction in testing a patient against pollens or proteins has been outlined by MacKenzie and Baldwin.1 Their preliminary experiments showed the degree and duration of the cutaneous exhaustion which might follow an initial test. At this time they anticipated "the probability that by local application of pollen or dandruff extracts to the mucous membrane of the nose and throat of patients with allergic rhinitis the reactivity might here also be abolished."
The observation on my part, that specific cutaneous sensitization might disappear over night from a very considerable part of the same forearm which previously had been tested and found positive, led me to consider the possibilities of applying therapeutically the principles underlying the phenomenon. This change in local reactivity was drawn to my attention by the more or less routine testing of both bronchial asthmatic and
CAULFEILD AHW. DESENSITIZATION OF HAY-FEVER PATIENTS BY INJECTION AND LOCAL APPLICATION. JAMA. 1922;79(2):125-128. doi:10.1001/jama.1922.02640020037010