Leukotrienes (LTs) are a group of acute inflammatory mediators derived from arachidonic acid in eosinophils, mast cells, and macrophages. Their biosynthesis proceeds via the 5-lipoxygenase (5-LO) pathway in which 5-LO converts arachidonic acid into LTA4 with 5(S)-HpETE as an intermediate. The conjugation of glutathione to LTA4 results in the formation of LTC4, which is then rapidly metabolized to LTD4 and LTE4. This metabolism is essentially complete within 10 minutes in the human lung. Cayman’s LTC4 ELISA Kit is a competitive assay that can be used for quantification of LTC4 in culture media and other sample matrices. The assay has a range from 17.1-5,000 pg/ml and a sensitivity (80% B/B0) value of approximately 40 pg/ml.