This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology Pa 1 (Immune Response, Antigen-Antibody Reactions, Hypersensitivity, Structure of Immune System, Immunodeficiency Disorders), Subject name: Microbiology
PK reaction detects 
Select and explain. 
A. IgG, B. IgA, C. IgE, D. IgM
C: IgE
Answer: C: IgE 
Explanation: The Prausnitz-Kustner test is an immunologic test formerly used by physicians to determine if a patient has an allergic reaction to a specific antigen. IgE is homocytotropic i.e. species specific. Only human IgE can fix to the surface of human cells. This is the basis of Prautnitz- Kustner reaction, which was the original method of detecting atopic antibody. Examples of Type I Hypersensitivity Reaction.