Decreased membrane fluidity in erythrocytes from patients with Crohn's disease.

In erythrocytes from patients with Crohn's disease, lower levels of membrane fluidity were demonstrated by means of electron spin resonance with 16-stearic acid spin label (SAL) but not 5- or 12-SAL, suggesting more apparent abnormality in the deeper portion of lipid bilayer. Membrane lipid analysis showed a significant increase of sphingomyelin, a decrease of phosphatidylcholine and decreased contents of polyunsaturated acyl-chains, particularly C18:2, of phospholipid, without alteration in the cholesterol to phospholipid molar ratio. The alteration in membrane fluidity appeared to be closely related to changes in membrane phospholipid classes and their acyl-chains. Among the plasma lipids, contents of esterified cholesterol, phospholipid, very low- and low-density lipoproteins and cholesterol of high-density lipoprotein significantly decreased. Decreased contents of polyunsaturated acyl-chains, particularly C18:2, in the plasma phospholipid were also noted. Changes in plasma and erythrocyte membrane lipids remained even in the inactive stage of the disease, except for the normalized sphingomyelin and phosphatidylcholine content in the erythrocyte membrane. Since membrane fluidity is closely involved in various cell membrane functions, the decreased membrane fluidity and altered lipid composition in erythrocyte membrane evident in patients with Crohn's disease may have important effects on the pathological status in this disease.