The test for passive cutaneous anaphylaxis (PCA) proved relatively simple and easy to perform. Within limits, the minimal amount of challenge Trichinella antigen was dependent on the amount of antibody used for sensitization. The optimal concentrations of Trichinella and Toxocara antigens to use in PCA tests with these experimental infections were determined. Studies with rabbit and guinea pig antisera indicate that antibodies involved in PCA reactions may differ from those involved in bentonite flocculation or hemagglutination tests. PCA reactions with heterologous antigens are common. The simplicity of the procedure is considered of distinct value and advantageous, but the amount of antigen required for a reaction and the possibility of cross-reactions are drawbacks.
Department of Microbiology, University of Missouri, Columbia, Missouri.