RESUMO
Cytokines from asthmatic mononuclear cells (MNC) cultured with Bermuda Grass pollen extract (BG), were tested for their effect on leukotriene B4 (LTB4) and platelet-activating factor (PAF) generation by neutrophil under calcium ionophore stimulation. Three groups were enrolled in this study: 9 allergic asthmatics showing skin intradermal test positive to BG, 12 non-allergic asthmatics and 5 normal individuals. Results showed that the stimulation index of BG on MNC and the mediator-release enhancing activity from both allergic and non-allergic asthmatics were similar; neither showed significant increase when compared to that of normal individuals. However, there was a significant increase in PAF-release-enhancing activity in unstimulated MNC supernatant from both allergic and non-allergic asthmatics (618 +/- 75 pg/10(6) neutrophils and 569 +/- 60 pg/10(6) neutrophils) when compared to that of normal individuals (460 +/- 40 pg/10(6) neutrophils). This PAF-release-enhancing activity did not correlate with either skin test reactivity or the amount of BG specific IgE antibodies. The PAF-release-enhancing activity in unstimulated MNC supernatants from asthmatics suggesting that there is a pre-activation of MNC which might contribute to the asthmatic reaction through generation of PAF by neutrophils.