ARA-derived PGD2 has been shown to play an important role in the pathogenesis of asthma and allergy via the activation of DP1 and CRTH2 (DP2) receptors [18], [19], and the fact that Δ12-PGJ3 shares structural similarity with Δ12-PGJ2, a product of PGD2 that is also known to bind to DP receptors [8], we evaluated the drug-induced hypersensitivity of Δ12-PGJ3 in various in vitro and in vivo models. This evidence concerns the gene PTGDR2 and asthma.