A comprehensive analysis of the role of the actin cytoskeleton in exocytosis of the four different neutrophil granule subsets had not been performed previously. Immunoblot analysis showed that, compared with plasma membrane, there was less actin associated with secretory vesicles (SV, 75%), gelatinase granules (GG, 40%), specific granules (SG, 10%), and azurophil granules (AG, 5%). Exocytosis o...

We evaluated the effects of alpha-Toc on surface expression of CD11b/CD18 on polymorphonuclear leukocytes (PMN) stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) and oxidized low-density lipoprotein (oxLDL). Incubation of PMN with fMLP (1 microM) or oxLDL (100 microg/mL) increased CD11b/CD18 expression; pretreatment with alpha-Toc reduced in a dose-dependent manner. PMN obtained fr...

Various n-formylated peptides function as receptor-specific chemoattractants for both granulocytes and monocytes. Because these agents are important tools in the study of leukocyte function in vitro, we chose to examine their effects on leukocyte procoagulant activity. The synthetic chemotactic peptide N-formyl-methionyl-leucyl phenylalanine (FMLP) induces a fourfold increase in procoagulant ac...

The bacterial tripeptide formyl-Met-Leu-Phe (fMLP) induces the secretion of enzyme(s) with phospholipase A(2) (PLA(2)) activity from human neutrophils. We show that circulating human neutrophils express groups V and X sPLA(2) (GV and GX sPLA(2)) mRNA and contain GV and GX sPLA(2) proteins, whereas GIB, GIIA, GIID, GIIE, GIIF, GIII, and GXII sPLA(2)s are undetectable. GV sPLA(2) is a component o...

Previous studies have shown that rabbit hearts subjected to in vivo left ventricular myocardial infarction and subsequent ex vivo perfusion respond to N-formylmethionyl-leucyl-phenylalanine (fMLP) with enhanced eicosanoid synthesis. This synthetic response occurs primarily in the right cardiac atrium, a site distant from the injury, and is not the result of increased enzymatic capacity for arac...

To examine whether activation of polymorphonuclear leukocytes attenuates release of adenosine through attenuation of their own ecto-5'-nucleotidase activity, human polymorphonuclear leukocytes were incubated with and without exposure to either N-formyl-methionyl-leucyl-phenylalanine (FMLP) or complement C5a. Ecto-5'-nucleotidase activity of polymorphonuclear leukocytes was attenuated by both FM...

A search for new targeted therapeutic strategies based on examining immunopathogenetic mechanisms emerging co-infections is relevant and may further contribute not only to optimizing choice of immunotropic drugs, but also achieving positive clinical immunological remission abnormal infectious processes. Previously, our studies found that recurrent viral-bacterial respiratory infections are asso...

Incubation of human neutrophils with a chemotactic peptide [N-formylmethionyl-leucylphenylalanine (fMLP)] gave rise to an increase in the phosphoinositide 3-kinase (PI3K) activity, phosphorylation of p47phox and superoxide-anion (O2(-)) generation in the same fMLP-concentration-dependent manner. These responses to fMLP were markedly enhanced when the cells had been incubated for 10 min before t...

Human peripheral blood neutrophils (PMN) plated onto fibrinogen and activated with FMLP release HtOt and lactoferrin, a specific granule component, with parallel kinetics. Although tumor necrosis factor-a (TNFa) only primes PMN in suspension, it is a potent agonist of adherent PMN. Activation of adherent PMN by FMLP (lo-’ mol/L) stimulated detectable release of TNFa within 45 minutes of stimula...

Neutrophils release reactive oxygen species (ROS) as part of the innate inflammatory immune response. Phosphoinositide 3-kinase gamma (PI3Kgamma), which is induced by the bacterial peptide N-formylmethionyl-leucyl-phenylalanine (fMLP), has been identified as an essential intracellular mediator of ROS production. However, the complex signalling reactions that link PI3Kgamma with ROS synthesis by...