Protective effects of the glucocorticoid, budesonide, on lung anaphylaxis in actively sensitized guinea-pigs: inhibition of IgE-but not of IgG-mediated anaphylaxis.

1 The effect of glucocorticoid pretreatment on antigen-induced bronchoconstriction was studied in guinea-pigs actively sensitized to two different ovalbumin regiments (one producing IgE- and IgG-like antibodies and the other exclusively IgG-like antibodies). 2 Budesonide (50 mg/kg) and hydrocortisone (50 mg/kg) given as one intraperitoneal injection 15-20 h before and anaphylactic tests or as two consecutive intraperitoneal injections 5 and 6 days before, led to a decreased bronchial capacity. In this respect glucocorticoid pretreatment was effective only in guinea-pigs sensitized to produce both IgE-like and IgG-like antibodies. 3 Budesonide pretreatment also reduced the capacity of anaphylactically-challenged chopped lung tissue to release histamine in guinea-pigs sensitized to produce both IgE- and IgG-like antibodies. 4 Budesonide pretreatment did not change the levels of circulating IgG1a and IgE-like homocytotropic antibodies as measured by passive cutaneous anaphylaxis; nor did it affect histamine or methacholine-induced bronchoconstriction in vivo or the capacity of histamine or methacholine to contract the guinea-pig isolated trachea preparation of the isoprenaline-induced relaxation of this preparation. 5 The selective inhibitory effects of budesonide and hydrocortisone on IgE-mediated but not IgG-mediated anaphylaxis and the relevance to human atopic disease are discussed.