Changing reactivity of caprine and ovine mononuclear phagocytes throughoutpart of the life cycle of Oestrus ovis: assessment through spontaneous andinductible NO production

The in vitro reactivity of monocyte-derived macrophages (MDM) from Oestrus ovis (O. ovis) artificially infested lambs and kids was determined by measu ring their production of nitric oxide (NO) during the course of infestation . In both species, crude antigenic preparations obtained from O. ovis first instar larvae (L1) were found to significantly (P < 0.01) inhibit this NO production, whereas O. ovis second instar (L2) extract stimulated it. Furth ermore, this NO production by MDM decreased during infestation and was rela ted to blood eosinophilia. It appears that crude antigenic extract from O. ovis modified the NO activity of macrophages from lambs and kids infested w ith O. ovis larvae. (C) Inra/Elsevier, Paris.