Membrane Fluidity Of Polymorphonuclear Leukocytes Research Articles

Polymorphonuclear leukocyte membrane fluidity and cytosolic Ca2+ content at baseline and after activation in essential hypertension

Polymorphonuclear leukocyte membrane fluidity and cytosolic Ca2+ content at baseline and after activation in essential hypertension

Oxatomide modifies membrane fluidity of polymorphonuclear leukocytes from children with allergic asthma

Plasma membrane fluidity of polymorphonuclear leukocytes (PMN) was investigated in 10 allergic asthmatic children before and after oxato-mide treatment. Membrane fluidity was studied by measuring the steady state fluorescence anisotropy of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated into polymorphonuclear leukocyte (PMN) plasma membranes. There was an increase in membrane fluidity at the surface of PMN from asthmatic children. Oxatomide treatment significantly decreased PMN membrane fluidity. These data suggest that oxatomide may induce changes in the physicochemical properties of the PMN plasma membrane in asthmatic subjects. These changes may modify the functional activities of PMN.

Polymorphonuclear integrins, membrane fluidity, and cytosolic Ca(2+) content after activation in essential hypertension.

The purpose of this research was to obtain further information about the role of polymorphonuclear leukocytes in essential hypertension. These cells could be involved in the pathogenesis of organ injury. Thirty subjects (14 men and 16 women) with essential hypertension were enrolled. In these subjects we determined, at baseline and after in vitro activation with 4-phorbol 12-myristate 13-acetate and N:-formyl-methionyl-leucyl-phenylalanine, the polymorphonuclear leukocyte membrane fluidity, obtained by labeling the cells with 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3, 5-hexatriene, cytosolic Ca(2+) concentration, obtained by marking the cells with Fura 2-AM, and integrin pattern (CD11a, CD11b, CD11c, and CD18), by using the indirect immunofluorescence with a flow cytometer. At baseline there was no difference in membrane fluidity between normal subjects and hypertensives, whereas hypertensives showed an increase in cytosolic Ca(2+) content and an increase of the phenotypical expression of CD11a, CD11b, and CD18. In normal subjects and in hypertensives, after activation, no variation was found in membrane fluidity and cytosolic Ca(2+) content. In normal subjects, after activation, we observed a significant increase of the expression of all adhesion molecules, whereas in hypertensives we found an increase of the expression of CD11b, CD11c, and CD18 but also a decrease of CD11a. The behavior of the polymorphonuclear leukocyte integrin profile may have several explanations, and in particular, the trend of CD11a after chemotactic activation may be related to its cleavage or to an altered integrin phosphorylation/dephosphorylation balance hypothetically present in this clinical condition.

Polymorphonuclear leukocyte membrane fluidity before and after activation in subjects with insulin resistance.

The aim of this research was the evaluation of polymorphonuclear leukocyte (PMN) membrane fluidity in subjects with insulin resistance. Insulin sensitivity, in fact, may be influenced by plasma membrane fluidity. We enrolled 19 subjects with insulin resistance previously demonstrated during an euglycemic hyperinsulinemic clamp. PMN membrane fluidity was studied by labeling intact cells with the fluorescent probe 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene and calculating the fluorescence polarization degree. The measurement was made before and after incubation of PMNs with two activating agents: 4-phorbol 12-myristate 13-acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (fMLP). The baseline data showed a reduction of PMN membrane fluidity in subjects with insulin resistance. After PMN activation with PMA and fMLP, no significant variation in membrane fluidity was present in PMNs from normals, while in those from subjects with insulin resistance a slight decrease in PMN membrane fluidity was found only after activation with fMLP. The behavior of PMN membrane fluidity, before and after activation, distinguishes insulin-resistant subjects from normal controls, although the effect cannot be directly correlated with the degree of insulin resistance.

Alterations in membrane fluidity of polymorphonuclear leukocytes from children with trisomy 21

We investigated plasma-membrane fluidity and heterogeneity of polymorphonuclear leukocytes (PMNs) obtained from seventeen children with trisomy 21. Membrane fluidity and heterogeneity were studied by measuring steady-state anisotropy and fluorescence lifetime of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated into plasma membranes. The fluorescence anisotropy values in unstimulated PMNs from children with trisomy 21 were significantly higher than those of the control group. The addition of the respiratory burst stimulus phorbol myristate acetate induced a stable and significant increase in fluorescence anisotropy in both groups. These results demonstrate a decrease in membrane fluidity. Moreover, distribution analysis of TMA-DPH lifetime values indicate a decrease in membrane heterogeneity in subjects with trisomy 21. These data suggest changes in the physicochemical properties of the PMN's plasma membrane at the lipid-water interface in children with trisomy 21.

Effect of Nedocromil Sodium on Polymorphonuclear Leukocyte Plasma Membrane

The effect of nedocromil sodium on the plasma membrane fluidity of polymorphonuclear leukocytes (PMNs) was investigated by measuring steady-state fluorescence anisotropy of 1-[4-trimethylammonium-phenyl]-6-phenyl- 1,3,5-hexatriene (TMA-DPH) incorporated in the membrane. Our results show that nedocromil sodium 300 μM significantly decreased membrane fluidity of PMNs. The decrease in membrane fluidity of PMNs induced by fMLP was abolished in the presence of nedocromil sodium. These data suggest that nedocromil sodium interferes with the plasma membranes of PMNs and modulates their activities.

Membrane fluidity of polymorphonuclear leukocytes from children with primary ciliary dyskinesia.

Plasma membrane fluidity and heterogeneity of polymorphonuclear leukocytes (PMN) were investigated in seven children with primary ciliary dyskinesia (PCD) and 17 healthy controls. Membrane fluidity and heterogeneity were studied by measuring the steady state fluorescence anisotropy and fluorescence decay of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated into PMN plasma membrane. Our results show an increase in membrane fluidity at the surface level of PMN from patients with PCD. Distribution analysis of TMA-DPH lifetime values indicate an increase in membrane heterogeneity in subjects with PCD. The observed changes in the physicochemical properties of the membrane could lead to alterations in the function of PMN from children with PCD.

Alterations in membrane fluidity of polymorphonuclear leukocytes from children with trisomy 21

Alterations in membrane fluidity of polymorphonuclear leukocytes from children with trisomy 21

Alterations in membrane fluidity of diabetic polymorphonuclear leukocytes

Plasma membrane fluidity of polymorphonuclear leukocytes was investigated in 28 patients with insulin dependent diabetes mellitus and 30 healthy controls. Membrane fluidity was measured by steady-state fluorescence anisotropy of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated into the plasma membrane. The fluorescence anisotropy values in resting (unstimulated) polymorphonuclear leukocytes from diabetic subjects were significantly higher than those of controls (0.318 +/- 0.003 vs 0.287 +/- 0.003, P less than 0.001). The addition of the respiratory burst stimulus phorbol myristate acetate induced a stable increase in fluorescence anisotropy values in both groups. Fluorescence anisotropy values of stimulated polymorphonuclear leukocytes from the diabetic and control groups were not significantly different (P greater than 0.05). These data demonstrate a decrease in plasma membrane fluidity of resting polymorphonuclear leukocytes obtained from diabetic subjects. This finding could be in part explained by an increase in their basal respiratory burst activity.

Decreased Fluidity of Polymorphonuclear Leukocyte Membrane in Streptozocin-Induced Diabetic Rats

Using flow cytometry with the excimer-forming lipid technique with pyrenedecanoic acid, we measured membrane fluidity of polymorphonuclear leukocytes (PMNs) from 20 streptozocin (STZ)-induced diabetic rats. Diabetes mellitus was induced in male Sprague-Dawley rats (body wt 243 +/- 11 g) with an injection of 25 mg/kg i.v. STZ. Membrane fluidity of PMNs was significantly lower at 2 wk after the STZ injection when serum glucose reached the plateau (31.1 +/- 5.8 mM), and after 3 wk, membrane fluidity remained unchanged. In 7 STZ-resistant rats for which serum glucose was less than 10 mM at 2 wk after the STZ injection, gradual normalization in membrane fluidity was observed. PMN membrane fluidity at each week correlated inversely with respective serum glucose levels 1 wk previously (r = -0.76) but not with serum lipid levels. Cross-incubation studies ascribed this observation to factors in the diabetic rat serum. Glycosylated protein, which was separated from diabetic rat serum, decreased membrane fluidity of control rat PMNs. Human diabetic subjects have an increased risk for infection, which may be due partly to altered membrane fluidity of their PMNs.

Decrease of Polymorphonuclear Leukocyte Membrane Fluidity in Uremic Patients on Hemodialysis

We measured membrane fluidity of polymorphonuclear leukocytes (PMN) from 14 uremic patients on hemodialysis by the excimer-forming lipid technique with pyrenedecanoic acid using flow cytometry. Membrane fluidity of PMN was significantly lower in the uremic patients during the predialysis period. During hemodialysis, progressive normalization in membrane fluidity was observed. Cross-incubation studies indicated that this observation is ascribed to factors in the patients' serum and that they can be removed by hemodialysis. When sera of these patients were fractionated by Sephadex G-25 column chromatography, the specific fraction responsible for a decreased fluidity was found in the low-molecular-weight fraction. Uremic patients have an increased risk of infection, which may be partly due to altered membrane fluidity of their PMN.

Measurement of membrane fluidity of polymorphonuclear leukocytes by flow cytometry

A method was established for measuring membrane fluidity of polymorphonuclear leukocytes (PMN) by the excimer-forming lipid technique with pyrenedecanoic acid in flow cytometry. When cells were labeled, the use of 2–25 μM of pyrenedecanoic acid provided similar results. Neither the removal of the unincorporated pyrenedecanoic acid nor adjustment of PMN counts exhibited any effect. By the gate analysis method, membrane fluidity of PMN could be measured with 100 μl of heparinized whole blood in a short time and results with PMN in whole blood was similar to those with purified PMN. Therefore, ourification and count adjustment of PMN could be omitted. By this method, membrane fluidity of PMN, which were treated with membrane fluidizer, was measured successfully. This method could be applied to the study of PMN function in various diseases.