Since 5-LO is essential for the biosynthesis of all LT derivatives, 5-LOX−/− mice are resistant to LT-associated inflammatory conditions, such as PMA-induced skin edema and immune complex peritonitis (i.v. ovalbumin followed by i.p. anti-ovalbumin IgG), in which 5-LOX−/− mice exhibited significantly reduced PMN infiltrates compared to wild-type mice (Chen et al., 1994). This evidence concerns the gene ALOX5 and edema.