Polarization and chemokinesis of ovine and human neutrophils in response to Fasciola hepatica excretory-secretory products.

The effect of Fasciola hepatica excretory-secretory products (ES products) on the polarization and chemokinesis of sheep and human neutrophils was investigated. Flukes were cultured overnight in RPMI-1640 medium, and the resulting ES products concentrated by dialysis (cut-off 1.2 kDa) before use. At the concentrations used toxicity tests showed no effect on neutrophil viability, but ES products were capable of causing morphological changes and chemokinesis in both sheep and human neutrophils. The polarizing effect of the ES products was found to be greater in the case of sheep neutrophils with 81% of cells polarizing at 80 micrograms total ES protein/ml as opposed to 36% of human neutrophils. Chemokinesis in response to 80 micrograms total ES protein/ml was significant (P < 0.01) in both species with sheep producing the stronger response. Delipidation of the ES products with Lipidex caused no loss of polarizing activity, nor did the purified lipid fraction show any polarizing effect. ES products lost polarizing activity after heat treatment or trypsin digestion. Preliminary fractionation on an S-300 Sephacryl column suggested the presence of at least four fractions capable of causing polarization in sheep neutrophils.