<prompt> Passive cutaneous anaphylaxis detect:Heterocytotropic abWheal and flare reactionAtopyCutaneous anaphylaxis  <response>: Ans. aPassive cutaneous anaphylaxis-in vivo method for detection of antibodies.Antigen injection intradermally then same antigen with a dye injected IV - after 4 to 24 hours - wheal flare reaction occurs in intradermal site.Helps to detect IgG ab which is heterocytotropic, not for IgM which is homocytotropic. 