Partial purification and biological properties of an eosinophil‐activating factor

Abstract

A protein (eosinophil-activating factor, EAF), which enhances the capacity of human peripheral blood eosinophils to kill antibody-coated schistosomula of Schistosoma mansoni, has been partially purified from supernatants of cultured peripheral blood mononuclear cells by sequential chromatography on Sephacryl S200 and DEAE-cellulose. This protein is acidic with a molecular mass on gel filtration of 40 +/- 7 kDa. It not only enhances the activity of eosinophils against schistosomula but also increases their ability to lyse antibody-coated, herpes simplex virus-infected Chang liver cells. It enhances the production of superoxide and hydrogen peroxide by eosinophils that occurs both spontaneously and in response to opsonized zymosan. However, increased respiratory burst activity does not appear to be responsible for the enhancement of eosinophil-mediated killing of schistosomula, since a comparable or greater increase in hydrogen peroxide production is induced by column fractions that have little or no effect on schistosomulum killing. EAF enhances eosinophil degranulation, both spontaneously and after incubation with opsonized zymosan. Enhanced degranulation is associated with release of eosinophil peroxidase and eosinophil cationic protein. These findings suggest that EAF enhances the capacity of eosinophils to kill parasites by increasing the extent of eosinophil degranulation and the amount of toxic granule proteins that are secreted.

New Properties and Roles for Eosinophils in Disease: Discussion Paper

“…Activation (in this strict sense) is comparable to macrophage activation, as in both cell types it is now known to be induced by lymphokines (Dessein et al 1982, Veith et al 1984. The eosinophil activating factor (EAF), which is distinct from the macrophage activating factor, has been isolated recently (Thorne et al 1985) and large amounts can now be made using cell lines (Silberstein et al 1985). Activation appears to be a final step in the development of the full biological properties of eosinophils.…”

Effect of Drugs Used in the Treatment of Asthma on the Production of Eosinophil-Activating Factor by Monocytes

“…At least part of the enhanced cytotoxic ac tivity is a consequence of activation by a blood mono cyte product, eosinophil-activating factor (EAF), which is secreted by monocytes from certain eosino philic donors [2][3][4], While conducting an investigation of the signifi cance of EAF in patients with asthma, it became clear that certain drugs used in the treatment of asthma in hibit EAF production by blood monocytes. EAF ac tivity was assayed by measuring the enhancement of eosinophil-mediated cytotoxic activity towards antibody-coated schistosomula of Schistosoma mansoni…”

“…The influence of the drugs on EAF-mediated acti vation of eosinophils was determined using EAF pu rified from blood mononuclear cell supernatants [3]. Eosinophils (50 ul) were pre-incubated for 1 h with EAF (50 pi) and either MEM containing FCS or the drug under test (50 pi at 5 times the final concentra tion).…”

Production of Eosinophil-Activating Factor (EAF) by Peripheral Blood Mononuclear Cells from Asthma Patients

“…EAF is the main eosinophil-activating activity produced by blood monocytes from moderately eosinophilic do nors (up to 3 x 10V(il) without further stimulation [8,9], It is a glycoprotein of molecular weight 40 kDa and pi 4.4. It induces release of ECP, superoxide and hydrogen peroxide and enhances opsonised zymo san-induced release of EPO and IgG-induced produc tion of LTC4 [6].…”

“…It induces production of superoxide and hydrogen per oxide. EAF-activated eosinophils stain positively with EG-2; they spontaneously secrete ECP and give enhanced secretion of EPO in response to opsonised zymosan [8], IgG-induced production of LTC4 is in creased [6]. Activation with EAF is associated with a marked change in cell morphology, with change in shape from spherical to elongated and production of granule-free lamellipodia containing polymerised actin [22,23].…”