Seven subjects shown by patch test to be sensitive to poison ivy oleoresin were challenged with graded oral doses of ivy extract. In each instance the circulating basophil leukocytes showed significant degranulation within one hour of challenge. This finding was interpreted as evidence of the presence of immediate-type circulating antibody to ivy antigen in these subjects. No drop in the absolute basophil count was noted, but with higher oral doses the degranulation persisted for several days. Thirteen control subjects showed no change in the basophil morphology or count, indicating that the resin at these levels was not toxic to this cell.
All but one of the sensitive subjects showed objective patch test evidence of hyposensitization following the intensive three-week course of oral poison ivy antigen.
SHELLEY WB, RESNIK SS. Basophil Degranulation Induced by Oral Poison Ivy Antigen. Arch Dermatol. 1965;92(2):147–150. doi:10.1001/archderm.1965.01600140035007
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