This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
All are functions of leukotrienes except: 
Select and explain. 
A. Increase vascular permeability., B. Broncho constrictors., C. Platelet aggregators., D. Counter regulatory compounds of immune system.
C: Platelet aggregators.
Answer: C: Platelet aggregators. 
Explanation: Satyanarayan -562
Leukotrienes are implicated in asthma, inflammatory reactions, hypersensitivity and heart attacks. Leukotrienes cause contraction of smooth muscles, bronchoconstriction, vasoconstriction, adhesion of white blood cells and release of lysosomal enzymes. Lipoxins are involved in vasoactive, and immunoregulatory functions. There is a strong evidence to support that lipoxins act as counter regulatory compounds of immune response.