5(S),15(S)-DiHETE is synthesized by 15-LO from 5(S)-HETE. It potentiates the degranulation of human PMNL in response to PAF, but not fMLP, calcium ionophore A23187, or LTB4. 5(S),15(S)-DiHETE is chemotactic for eosinophils with an ED50 value of 0.3 μM.