The non-specific enhancement of allergy. III. Precipitation of bronchial anaphylactic reactivity in primed rats by injection of alum or B. pertussis vaccine: relation of response capacity to IgE and IgG2a antibody levels.

SD rats were sensitized by an i.p. injection of 1 microgram or 10 micrograms ovalbumin (OA) together with 10 mg Silica gel. At the indicated time after sensitization, allergic response capacity of the animals was estimated by measuring changes in intratracheal pressure induced by an i.v. injection of 0.3 mg OA (low challenge dose) or 5 mg OA (high challenge dose). Animals given 1 microgram OA in Silica gel showed no response capacity at 14, 35 or 47-48 days after sensitization. Animals injected with 10 micrograms OA showed a clear-cut response with a peak at 14 days; at 7 weeks after immunization the response capacity had faded almost completely. Specific OA-IgE antibody and total IgE serum levels were examined by radioimmunoassay. A slight increase in OA-IgE antibody was recorded in animals injected 14 days before test with 10 micrograms ovalbumin and Silica gel; animals given 1 microgram OA and Silica showed no OA-IgE antibody. Five weeks after sensitization, some animals of each group were injected i.p. with 100 mg alum, B. pertussis vaccine (2 ml of Perthydral), or saline, all injections being made without any further antigen addition. 12-13 days after such an injection, alum-treated animals showed high response capacity at bronchial anaphylactic tests and high OA-IgE antibody levels but comparably low levels of total IgE. Animals injected with B. pertussis, on the other hand, showed low response capacity (bronchial anaphylactic tests and OA-IgE antibody levels) but high total IgE-antibody levels. The bronchial anaphylactic response in the B. pertussis-injected animals but not the alum-injected animals was significantly correlated to serum IgG2a antibody levels. These results show that injection of alum or B. pertussis vaccine without antigen can precipitate/enhance anaphylactic response capacity and production of specific and non-specific IgE and IgG2a.