Effect of glycerolipid preparations from fern and horsetail on human peripheral blood mononuclear cells under ex vivo conditions

Introduction. Human peripheral blood mononuclear cells (PBMCs) are a pool of immune cells and they are also a convenient model system for studying immune pathologies.Aim. Testing for bioactivity of glycerolipid prepa­rations from fern and horsetail species containing long chain polyunsaturated fatty acids (LCPUFAs) towards PBMCs without exogenous stimulation and after phorbol-12-myristate-13-acetate (PMA) plus ionomycin stimulation.Materials and methods. Glycerolipid preparations were produced by fractionation of total lipids, isolated from young fronds of the fern Matteuccia struthiopteris and shoots of the horsetail Equisetum arvense, on silica. Egg phosphatidylcholine was used for comparison. Fatty acids were analyzed by gas chromatography. Mononuclear cells were isolated from blood of patients with asthma. Parameters of cell viability and activation were estimated by flow cytometry.Results. The glycerolipid prep­arations from the fern and horsetail were found to have a cytotoxic effect while egg phosphatidylcholine was not. The most active was the fraction of fern lipids eluted with methanol which reduced cell viability by 64.6 (51.1-79.0)% in the concentration 2 pg/ml and caused complete cell death in 20 pg/ml. After cell stimulation with PMA/ionomycin, the cyto­toxic effect of the preparation increased although the level of PBMCs expressing the marker CD69 did not change. The cytotoxic effect of other glycerolipid preparations was observed in the higher concentrations (20 and/or 80 pg/ml) and it was less pronounced: the cell viability reduced by 7.1 (6.7-9.4)% for the fraction of fern lipids eluted by the mixture chlo­roform - methanol - water (3:5:2), by 39.8 (26.4-41.6)% and 12.0 (10.0-15.5)% for the fractions of the horsetail lipids eluted with methanol and the chloroform-methanol-water mixture, respectively, in the concentration 80 pg/ml.Conclu­sion. Comparison of fatty acid composition of the glycerolipid preparations did not confirm a contribution of LCPUFAs to the observed effects. Identification of an active component may allow development of a drug for the local application in a hyperimmune response or for model experiments.