The Pharmacology of Passive Cutaneous Anaphylaxis in the Calf

The effects of mepyramine maleate, sodium meclofenamate, methysergide bimaleate, diethylcarbamazine citrate, and disodium cromoglycate on bovine cutaneous anaphylactic reactions and responses to intradermal injections of histamine, 5-hydroxytryptamine, and bradykinin were studied. Calves sensitized by immunization with horse serum in Freund's complete adjuvant were bled to obtain skin-sensitizing serum which was used in passive cutaneous anaphylaxis (P.C.A.) tests. A latent period of 72 h was allowed between intradermal injections of sera and antigen challenge. Mepyramine maleate (10 mg/kg) selectively inhibited responses to histamine and raised the threshold dose of antibody required to elicit a response. Disodium cromoglycate (DSCG, 10 mg/kg) given intravenously 30 min or immediately prior to challenge had no significant effect either on the responses to drugs or on the passive cutaneous anaphylaxis reaction. Diethylcarbamazine (DECC, 20 mg/kg) administered immediately prior to challenge significantly inhibited the cutaneous anaphylactic response and when DSCG was given simultaneously with DECC, this inhibitory effect was apparently augmented. Methysergide (1 mg/kg) and sodium meclofenamate (2 mg/kg) were ineffective in suppressing P.C.A. It is concluded that histamine and a slow-reacting substance (SRS-A) are involved in the mediation of bovine cutaneous anaphylaxis and that kinins may contribute, while 5-hydroxytryptamine would appear unimportant.