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N Frickhofen

Publications and source records attributed to N Frickhofen.

8 recordsLinked to original sources
PubMed1979

Eosinophil chemotactic factor. Release from human polymorphonuclear neutrophils by arachidonic acid.

An eosinophil chemotactic factor (ECF) can be released from human polymorphonuclear neutrophils by arachidonic acid (AA), its methyl ester, but not by other derivatives such as AA ethyl ester and arachidonyl acetate. The ECF is highly specific for eosinophils and does not attract polymorphonuclear neutrophils. A dose-dependent non-cytotoxic ECF release induced by AA can be obtained from human polymorphonuclear neutrophils from a lymphocyte-monocyte-basophil suspension, from rat basophil leukemia cells, but not from human lymphocytes. Kinetic studies demonstrate that ECF release occurs rapidly with an early rise and steep fall-off at later times of secretion. The amount of ECF release is dependent on pH, temperature and medium which is used for stimulation. Gel filtration analysis as well as subcellular fractionation studies suggest that the AA-induced ECF is a biological activity either distinct from AA and its split products or representing a known or unknown conversion product of AA with potent effects on eosinophils at minimal concentrations. AA may therefore represent an important mechanism of cell activation.

Animals↗
PubMed1979

Generation and secretion of eosinophilotactic activity from human polymorphonuclear neutrophils by various mechanisms of cell activation.

An eosinophil chemotactic factor(s) (ECF) can be generated from human polymorphonuclear neutrophils by the calcium ionophore, phagocytosis, arachidonic acid and hypotonic lysis. In kinetic studies it is observed that peak ECF activity is released prior to the maximum of lysosomal enzyme release with the calcium ionophore, phagocytosis and arachidonic acid, while under conditions of hypotonic exposure ECF activity appears after the maximum of enzyme release. The ECF obtained by hypotonic exposure shows a fluctuating pattern with sharp peaks and steep fall-offs in activity. The ECF-release for each stimulus is temperature dependent; extracellular calcium is required when the ionophore or phagocytosis are used as stimuli, while with arachidonic acid and hypotonic exposure no extracellular calcium is necessary for ECF-release. On Sephadex G-25 each preparation of ECF eluted in the low molecular weight range at approximately 500 daltons. Eosinophils can be deactivated and cross-deactivated with the various ECF-preparations indicating either a molecular identity or a common mode of action on eosinophils.

Arachidonic Acids↗
PubMed1979

Subcellular localization of the eosinophil chemotactic factor (ECF) and its inactivator in human polymorphonuclear leucocytes (PMN).

An eosinophil chemotactic factor (ECF) of low MW can be released from human polymorphonuclear leucocytes (PMN) on stimulation with the Ca-ionophore, arachidonic acid and during phagocytosis. After a rapid rise of ECF activity in the supernatant a steep fall of in its activity occurred at the later times of secretion suggesting a mechanism of ECF inactivation. ECF obtained at the later times of secretion represents a stable biological activity and does not decrease on further incubation. In addition, intact PMN and ECF combined do not lead to its inactivation, while incubation of homogenized PMN with ECF decreased its activity. These data suggest the presence of an inactivator for ECF within human PMN. The purpose of the study was to localize ECF and its inactivator within human PMN. After cell disruption, differential and equilibrium gradient centrifugation, subcellular components of human PMN can be obtained which reveal eosinophilotactic (ECF) or ECF-inactivating activity. ECF activity can be recovered (in a structurally bound state) from the microsomal fraction of unstimulated and stimulated PMNs, while another portion is obtainable as a soluble, low mol. wt ECF. The PMN-derived ECF inactivator can be recovered from the peroxidase positive (azurophilic) granules and has a mol. wt of 60,000 and less. We suggest that low mol. wt ECF is derived from the plasma membrane of PMN which can be inactivated by components of the azurophilic granules. The mechanism of inactivation is still unresolved.

Arachidonic Acids↗
PubMed1978

Generation and release of eosinophil chemotactic factor from human polymorphonuclear neutrophils by arachidonic acid.

This study describes the generation and release of an eosinophil chemotactic factor from human polymorphonuclear neutrophils, rat basophilic leukemia cells, and from a lymphocyte monocyte basophil suspension by arachidonic acid (AA). The eosinophil chemotactic factor (ECF) is highly specific for eosinophils and resembles the ECF activity obtained from human polymorphonuclear neutrophils after stimulation with the Ca ionophore or during phagocytosis. In this regard, AA-induced ECF represents a biological activity distinct from oxidized AA and its conversion products. AA may therefore have a dual function: it represents an important mechanism of cell activation; as AA is converted into prostaglandins, it appears likely that they exert a modulatory and a suppressive role on biological functions, such as chemotaxis and phagocytosis.

Animals↗