Decreased membrane "fluidity" of T lymphocytes from untreated patients with Hodgkin's disease

Membrane fluidity characteristics of human lung cancer

Membrane fluidity of non-cultured lung cancer tissue was studied by electron paramagnetic resonance (EPR). EPR spectra of a lipophilic spin probe in a tissue of resected tumor samples from 51 patients were compared with computer simulated spectra, which were superimpositions of spectra characterizing membrane domains with different fluidity. The membranes of tumor tissues were more fluid, than those of normal lungs; the most fluid domains were enlarged and their order parameter decreased in comparison to normal tissue. An empirical fluidity parameter (H13) was defined as the criterion to correlate EPR and clinical data. The histology of tumor, the quantitative presence of different tumor and non-tumor cells and the pathohisthological stage of the disease had no significant influence on fluidity.

Characterization of lipid composition in stimulated human lymphocytes by 1H-NMR

Recent in vivo NMR studies have raised interest in the structural changes of cellular lipids during proliferative activity. We investigated the changes in plasma membrane lipid and total cell lipid during mitogenically-stimulated proliferation of human peripheral blood lymphocytes by extraction of lipids and assay by 500 MHz 1H-NMR. Resonances were assigned using one- and two-dimensional spectroscopic techniques, and signals unique to certain species of lipid were identified. Choline and ethanolamine-containing lipids, glycerophospholipid backbones, sphingolipids, cholesterol, plasmalogens and triacylglycerols were readily detected. Resolution of a number of lipid species was not possible, despite the use of high-resolution techniques. NMR values for proliferation-induced changes in the most easily determined parameters, namely the total cholesterol to total phospholipid molar ratio, and phosphatidylcholine, phosphatidylethanolamine and sphingolipid composition, were found to agree with traditional methods. Differences in phospholipid and fatty acid profiles were found between plasma membranes and total cell lipid for resting values and for response to mitogen.

Plasma membrane fluidity gradients of human peripheral blood leukocytes

The shape of the fluidity gradient of the outer hemileaflet of the plasma membrane of normal, living, human white blood cells was determined using a series of n-(9-anthroyloxy) fatty acid probes where n = 2, 3, 6, 7, 9, 11, 12, and 16, to establish a baseline for future studies on the consequences of various pathological states. Fluorescence uptake and steady-state anisotropy values were obtained with a flow cytometer capable of continuous recording over time of vertical and horizontal emission intensities, with the output of these intensities as calculated anisotropy values. The fluorescence uptake of all of the membrane probes was rapid up to about 15 min. The magnitudes of the uptake of fluorescence was, for the n-(9-anthroyloxy) series, in the order 2 greater than 3 greater than 6 greater than 7 greater than 9 greater than 11 = 12 = 16 for neutrophils, lymphocytes, and monocytes. Anisotropy values were constant from 5 to 30 min after addition of the various probes. The orders of the anisotropy magnitudes, indicative of the shapes of the fluidity gradient, were, for neutrophils, 6 greater than 7 greater than 9 greater than 2 = 3 = 11 = 12 greater than 16, for lymphocytes, 7 greater than 6 greater than 9 greater than 11 greater than 2 = 3 greater than 11 = 12 greater than 16, and for monocytes, 9 greater than 7 greater than 6 greater than 11 greater than 2 = 3 greater than 12 greater than 16. The kinetics of anisotropy from 1 to 5 min after addition of the probes differed for each of the three cell types. Probes with an n-value less than or equal to the maxima (n = 6, neutrophils; n = 7, lymphocytes; n = 9, monocytes) rapidly (1.2 min) reached equilibrium, whereas those probes with n-values greater than the maxima took progressively longer times to equilibrate as n increased. This behavior is consistent with the existence of an energy barrier just below the approximate region sensed by the probes, which would correspond to just below 6AS for neutrophils, 7AS for lymphocytes, and 9AS for monocytes.

Cyclic AMP and cyclic GMP phosphodiesterase activities in Hodgkin's disease lymphocytes

Cyclic nucleotide phosphodiesterase (PDE) activities were studied in peripheral blood monocyte-depleted lymphocytes and enriched T-lymphocyte suspensions from thirteen patients with previously untreated Hodgkin's disease (HD) and fourteen age and sex matched healthy volunteers. Monocyte-depleted lymphocytes from HD patients showed PDE-activities which were two times higher than in their normal counterpart cells. The mean cAMP-PDE activity present in enriched HD T-lymphocyte suspensions was four times higher than in control T-lymphocytes, and the mean cGMP-PDE associated with HD T-lymphocytes was three times higher than in the controls. The hydrolytic activities present in both monocyte-depleted and T-lymphocyte enriched cells suspensions remained unchanged in absence or in the presence of calmodulin and calcium. Since depressed cAMP and cGMP resting levels have been observed in HD lymphocytes and lymphocyte subpopulations, our results suggest that the elevated PDE activities are, at least in part, responsible for the alterations in lymphocyte cyclic nucleotide levels.