The effect of ovine peripheral blood mononuclear cells on Haemonchus contortus larval morbidity in vitro.

Abstract

The objective of this study was to determine the effects of peripheral blood mononuclear cells (PBMC), derived from parasite-resistant St. Croix (STC) hair sheep and parasite-susceptible Suffolk (SUF) sheep, on Haemonchus contortus Lstage larval death in vitro, with or without autologous serum. Larval morbidity was quantified by measuring larval ATP concentration following incubation with PBMC. Larvae exposed to either STC- or SUF-derived PBMC had lower ATP than live larvae (0.12&#xa0;&#x3bc;mol/L ATP and 0.16&#xa0;&#x3bc;mol/L ATP vs 0.27&#xa0;&#x3bc;mol/L ATP, respectively) (P<.001) and greater ATP of dead larvae (0.03&#xa0;&#x3bc;mol/L ATP) (P<.001). Breed differences were observed with addition of autologous serum. Larvae exposed to SUF-derived PBMC with autologous serum were not significantly different from live larval ATP. STC-derived serum did not significantly reduce larval ATP compared to PBMC alone (0.11&#xa0;&#x3bc;mol/L ATP), but was significantly reduced compared to live larvae (0.22&#xa0;&#x3bc;mol/L ATP) and SUF-derived PBMC with autologous serum (0.23&#xa0;&#x3bc;mol/L ATP) (P<.001). These data indicate that a cellular response alone is capable of significantly reducing larval ATP in a breed-independent manner. However, addition of serum to SUF-PBMC failed to reduce larval ATP, indicating breed-dependent humoral response to H.&#xa0;contortus.