Assessment of neutrophil leukocyte secretory response to fMLP in whole blood in vitro

Abstract

A simple, precise method has been developed for assessing neutrophil secretory responses (release of vitamin B12 binding protein from specific granules) to challenge of aliquots of whole blood with the bacterial chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (fMLP). Dose-response studies performed on blood from normal healthy volunteers showed higher maximal secretory responses in males than females (33.3 +/- SEM 2.2 vs. 27.4 +/- 2.5, P less than .005) a left shift in dose-response curves after feeding compared to fasting (P less than .005), spontaneous up-regulation of responses in blood incubated at 37 degrees C for 1 h, and marked upregulation in response to preincubation with endotoxin. This whole blood challenge method may be used to study neutrophil responses in groups of individuals or patients without the confounding effects of changes in cell responses resulting from cell isolation procedures. The method may also be used as a bioassay for neutrophil-activating factors.

Expression of CD35 (CR1) and CD11b (CR3) on circulating neutrophils and eosinophils from allergic asthmatic children

“…In accordance with a study of Fearon and Collins [22], this up-regulation was maximal at a concentration of 0-02 /IM fMLP. Since the CDllb is localized in the specific granules of neutrophils [26], this result is consistent with the findings that the maximal release of vitamin B12 binding protein [27] and maximal chemotaxis [28] occur at 0-01 //H of fMLP.…”

Dose response of enoxaparin at the cremaster muscle flap microcirculation

“…During transmigration, leukocytes express their state of activation by biochemical changes, including degranulation with release of proteolytic enzymes (e.g., elastase, myeloperoxidase), and leading to interstitial inflammation, capillary compression, and reduced perfusion. 22,24 It was demonstrated that heparin preparations inhibit heparinase-mediated degradation of heparan-sulfate moieties of the extracellular matrix, inhibit the migration of leukocytes to extracellular sites, and prevent acute inflammation. 25,26 In our experimental model, each of the above mechanisms may play a role in improved capillary perfusion after enoxaparin injection.…”

Interleukin-8 Expression by Human Neutrophils Activated byHelicobacter pyloriSoluble Proteins

“…It can, however, elicit neutrophil chemotaxis across epithelial monolayers in vitro (40) and increase permeability and blood flow in the rat small intestine (41). Neutrophil activation may be augmented by other bacterial products (42), and IL-8 expression by neutrophils is significantly enhanced by the addition of LPS (16), suggesting a synergistic response. Therefore, fMLP secreted from H. pylori may permeate the gastric mucosa via damaged epithelial cells and, in the presence of other chemoattractants, potentiate chemotaxis and the activation of neutrophils.…”