FIG. 2.

Effects of ISL 929 and ISL 1373 on salivary inhibition of O₂⁻ production by PMN. Freshly isolated PMN were pretreated with saliva (1:10 dilution for 1 h at 37°C) from control-injected or dsRNA-injected ticks and assessed for O₂⁻ release by chemiluminescence assay following stimulation with PMA. (A) Representative plot showing O₂⁻ production by PMN in the presence (•) and absence (⧫) of stimulation by PMA and inhibition of O₂⁻ production by treatment with control (▪) but not by treatment with dsRNA (▴) saliva. (B) The peak value of O₂⁻ production (total up to 10 min) by the treated groups relative to that of the untreated group shows inhibition of O₂⁻ production by control but not by dsRNA saliva. *, P < 0.03 for PMN treated with control saliva versus untreated PMN; **, P < 0.004 for PMN treated with control versus dsRNA-treated saliva; there were no significant differences in O₂⁻ production by untreated and dsRNA-treated groups (paired t test; n = 5). The error bars indicate standard deviations. (C) PMN were treated with recombinant ISL 929 and ISL 1373 (2 μg/10⁶ cells) prior to stimulation by PMA and O₂⁻ assay. •, PMA stimulation; ▵, pretreatment with ISL 929; □, pretreatment with ISL 1373. The data shown are the means ± SEM; P < 0.001 for each protein treatment compared to no treatment at peak stimulation (paired t test; n = 6).