Passive Sensitization of Human Skin by Sera of Guinea Pigs Anaphylactically Sensitized to Ovalbumin

Previous studies have shown that immediate urticarial reactions of the Prausnitz-Kustner type may be produced in human skin after passive sensitization with sera from rabbits sensitized with ovalbumin and with sera from guinea pigs sensitized to pollens of grass or ragweed 1 , 2 . The present study concerns the activity in passively sensitizing human skin of sera from guinea pigs sensitized with crystalline ovalbumin, and the relationship of that activity to the capacity of the same anti-sera to produce passive anaphylactic sensitivity in the guinea pig.

Samples of sera obtained from guinea pigs sensitized by various methods at the Allergen Research Division of the Department of Agriculture were tested in the passive sensitization of human skin at Roosevelt Hospital. Other portions of the same antisera were tested in the passive anaphylaxis of guinea pigs at the Allergen Research Division.

Methods. To determine activity in passive anaphylaxis, serial dilutions of each serum (differing by a factor of 1.5) were injected intraperitoneally into normal guinea pigs weighing 280-310 g. These animals were challenged 2 days later with intravenous injections of 1 mg of ovalbumin. Assays were considered satisfactory if 2 of the serial dilutions produced nonfatal reactions and the 2 succeeding lower dilutions produced fatal anaphylaxis. The anaphylactic titer was expressed in terms of the number of fatal sensitizing doses per ml of serum. Skin-sensitizing activity was determined by injecting 0.1 ml of serum intracutaneously on the back or upper arm of a normal human test subject, shown by previous skin tests not to be allergic to ovalbumin or guinea pig serum. Twenty-four to 48 hours later 0.05 mg of ovalbumin, dissolved in 0.025 ml of saline, was injected intracutaneously into the same site. All sera were tested on two different volunteers. Reactions were observed after 15 minutes. Sites showing positive reactions were retested in serial dilutions to measure the skin-sensitizing antibody, the titer being the highest dilution producing a distinct reaction.