Anaphylactic reaction in smooth muscle from the duck

1. To know if the absence of desensitization in the chicken is characteristic of avian tissues, we studied the anaphylactic reaction in the duck. The contractions elicited in pieces of small intestine of actively immunized ducks upon exposure to the specific antigen, or Schultz-Dale reaction, were compared to similar responses of sensitized chicken and guinea pig intestine. 2. The smooth muscle from chicken actively sensitized contracts, when it is exposed in vitro to the specific antigen. Maximal tension, developed during anaphylactic reaction, is kept until the preparation is washed. New exposure of the muscle to the antigen causes it to develop tension again. This means that exposure to the antigen does not desensitize chicken intestine. 3. Intestinal smooth muscle from sensitized duck developed tension when the specific antigen was added to the bath; the tension was transitory and soon reached the basal line, even before washing the antigen. Contrary to the observations in the chicken smooth muscle, a second antigen dose failed to elicit a contraction of the duck intestine. Duck smooth muscle behaved like mammalian tissue. Exposure to the antigen desensitized duck intestine. 4. On multiple sensitized duck, the order of addition of antigens and their desensitization, did not alter the anaphylactic response to each antigen. 5. These observations are discussed in terms of the known properties of duck antibodies.