A glycoprotein antigen has been isolated from cured tobacco leaves (TGP-L) Nicotiana tabacum) and from cigarette smoke condensate (TGP-CSC) to which approximately one-third of human volunteers, smokers and non-smokers, exhibit immediate cutaneous hypersensitivity. TGP-L and TGP-CSC contain polyphenol haptens that activate the factor XII (Hageman factor) dependent pathways of coagulation, fibrinolysis, and kinin generation in normal human plasma. The purpose of this communication is to describe the isolation antigens from cocoa powder (Theobroma cacao), ground coffee (Coffea arabica), and ragweed (Ambrosia eliator) pollen that are immunologically cross-reactive with TGP-L and TGP-CSC, contain similar polyphenol haptens, and are capable of activating factor-XII-dependent pathways in normal human plasma.