A comparison of eosinophil‐activating factor (EAF) with other monokines and lymphokines

Monocytes from moderately eosinophilic individuals secrete material that enhances the cytotoxic activity of eosinophils against antibody‐coated schistosomula of Schistosoma mansoni. This material is not a single substance, but can be fractionated into several active components of different size and different charge. Gel filtration of mononuclear cell supematants separated the eosinophil‐activating activity into a major component of molecular mass of 40 kDa and a minor component of molecular mass of < 10 kDa. The major component exhibited further heterogeneity on fractionation by high performance liquid chromatography. The bulk of the eosinophil‐activating activity could be separated from both colony‐stimulating factor (CSF)α activity and from tumor necrosis factor (TNF) activity. However, human recombinant CSFα (GM‐CSF), human recombinant TNF and rabbit tumor necrosis serum all had eosinophil‐activating activity when tested against schistosomula. Eosinophils were not activated by interleukin 1, interleukin 2, interferon‐α, lipopolysaccharide or phorbol myristate acetate.