<prompt> Bronchospasm is initiated by?C5aC3aLeukotrienesAcetylcholines  <response>: Ans. c LeukotrienesRef: Robbins 9thpg 89LTE4 cause intense vasoconstriction, bronchospasm importantin asthma, and increased permeability of venules.C3a, C5a, and, to a lesser extent, C4a stimulate histamine release from mast cells and thereby increase vascular permeability and cause vasodilation. They are called anaphylatoxins 