The level of which one of the following compounds is elevated in bronchial asthama

Mediators such as histamine,PGD2, & cysteinyl-leukotrienes have been implicated in the pathogenesis of asthma.They contract airway smooth muscle,increase microvascular leakage,increase airway mucus secretion,and attract other inflammatory cells.They are released from the inflammatory cells like mast cells,eosinophils,basophils,etc. Reference:Harrison' s medicine,18th edition,page no:2106.