The Non‐Specific Enhancement of Allergy

Abstract

PVG rats given injections of 1 microgram ovalbumin (OA) together with 10 mg Silica gel failed to provide serosal mast cells or lung tissue with the capacity to release histamine on in vitro challenge with the antigen. However, if such animals were injected i.p. with 100 mg of alum (without any further antigen addition) 3-9 weeks after the primary antigen injection, their mast cells and lung tissue showed a clear-cut capacity to respond in vitro, when examined 1 week after the alum injection. Injection of only 15 mg alum did not induce such a response capacity. The fading of the reactivity induced by an alum injection could be prevented by a repeated injection of the adjuvant alone. Pretreatment of the rats with cyclophosphamide (33 mg/kg) 2 days before the primary antigen injection did not affect the response capacity induced by a booster injection 3 weeks later. S.c. injection of alum also precipitated response capacity in animals primed by i.p. injection of antigen and Silica gel. The anaphylactic response capacity induced by injection(s) of alum was generally accompanied by increased levels of OA-IgE and especially OA-IgG2a antibody; however, a clear-cut correlation between either serosal mast cell or lung tissue response capacity and serum OA-IgE or IgG2a antibody titer could not be demonstrated. These data show that in primed animals, which do not express allergic response capacity, such a capacity can be induced by injecting adjuvant alone, even several weeks after the primary antigen injection.