ARACHIDONIC ACID CORRELATION WITH SUSPENDED AND ATTACHED NEUTROPHILS

Abstract

Background: Neutrophils are the blood cells for which adhesion is one of the main functions. Neutrophils adhered to biological surfaces show different characteristics of activation compared with neutrophils in suspension. The respiratory burst in suspended neutrophils in response to a chemotactic factor is lower when compared with the cells attached to the surface. Objectives: This study aimed to study the role of arachidonic acid release in suspended and attached neutrophils following stimulation of human neutrophils with LPS and PAF. Materials and methods: The suspended and attached neutrophils were primed by LPS and PAF, and inhibited by Anti-CD 14 (MY4). Results: The arachidonic acid release in attached cells is more than in suspended cells. This release is rapid with the increase of incubation time and dose-depended. The Fmet-Leu-Phe (FMLP) potentiates arachidonic acid release in attached cells pretreated with LPS and serum. Arachidonic acid release was less in suspended cells in comparison to attached cells where the addition of low concentration of LPS in presence of serum or platelet activating factor (PAF) to suspended cells produce increase in arachidonic acid release. On the other hand LPS in combination with PAF produce a large and significant increase in arachidonic acid release. The potentiative effect of LPS is mediated via CD14 receptors. The monoclonal antibodies against CD14 had no effect on arachidonic acid release in PAF treated cells where it inhibited greatly the potentiation by LPS or LPS-serum complex with PAF. Conclusion: LPS or PAF alone produced small increase in arachidonic acid release in both suspended and attached human neutrophils, where LPS in combination with PAF induced significant arachidonic acid release in suspended and attached human neutrophils.