Local effect of single stranded polyadenylic acid on passive cutaneous anaphylaxis in mice

Single stranded polyadenylic acid (Poly A) administered locally inhibited passive cutaneous anaphylaxis in mice. In experiments performed by equilibrium dialysis Poly A was able to bind histamine. The association constant of the reaction was determined, Ka = 1.3 +/- 0.2 x 10(5) I/M. One Poly A molecule can bind maximally two molecules of histamine dichloride. Poly A inhibited the antigen-induced release of histamine from the peritoneal rat mast cells when it was given together with sensitizing antibodies.